| title: | 1.5 Cell R.F. Gun Simulation with coil and Space Charge U.C.L.A. IRFEL Note H.3 |
| format: | unpublished |
| year published: | January 9, 1990 |
| year authored: | 1990 |
| authors: | S. Hartman |
| abstract: | Simulations were done to explore the effect of placing a coil along the beamline to minimize the divergent lense effect of the exit of the last cell of the gun....etc. |
| title: | 25 MeV Injector for the Plasma Beat Wave Accelerator |
| format: | unpublished |
| year: | 1994 |
| authors: | C. Joshi,M. Lampel,S. Park,C. Pellegrini,R. Zhang |
| abstract: |
| title: | 3.5 Cell R.F. Gun Simulation with Spacecharge and Focusing Coil U.C.L.A. IRFEL Note H.1 |
| format: | unpublished |
| year published: | November 9, 1989 |
| year authored: | 1989 |
| authors: | S. Hartman |
| abstract: | Using the particle simulation code PARMELA, I calculated the emittance values for a three and one half cell gun. Since the beam suffers a R.F. defocusing at the exit of the last cell a solenoidal focusing element was added to cancel the divergence effect. |
| title: | 40 Angstrom FEL designs for the PEP storage ring |
| conference: | 13th International Free Electron Laser Conference |
| year published: | 1992 |
| year authored: | 1991 |
| authors: | A. Fisher,J. Gallardo,H. Nuhn,R. Tatchyn,H. Winick,C. Pellegrini |
| abstract: | Explores the use of the 2.2 km PEP storage ring at SLAC to drive a 40 angstrom free-electron laser in the self-amplified spontaneous emission configuration. Various combinations of electron-beam and undulator parameters, as well as special undulator designs, are discussed. Saturation and high peak, in-band, coherent power (460 MW) are possible with a 67 m, hybrid permanent-magnet undulator in a ring bypass. A 100 m, cusp-field undulator can achieve high average, in-band, coherent power (0.25 W) in the main ring. The existing, 25.6 m Paladin undulator at LLNL, with the addition of optical-klystron dispersive sections, is considered for both peak and average power. (35 References). |
| title: | A 2 to 4 nm high power FEL on the SLAC linac |
| conference: | 14th International Free Electron Laser Conference |
| year published: | 1993 |
| year authored: | 1992 |
| authors: | C. Pellegrini,J. Rosenzweig,H. Nuhn,P. Pianetta,R. Tatchyn,H. Winick,K. Bane,P. Morton,T. Raubenheimer,J. Seeman,K. Halbach,K. Kim,J. Kirz |
| abstract: | The authors report the results of preliminary studies of a 2 to 4 nm SASE FEL, using a photoinjector to produce the electron beam, and the SLAC linac to accelerate it to an energy up to 10 GeV. Longitudinal bunch compression is used to increase ten fold the peak current to 2.5 kA, while reducing the bunch length to the subpicosecond range. The saturated output power is in the multi-gigawatt range, producing about 10/sup 14/ coherent photons within a bandwidth of about 0.2% r.m.s., in a pulse of several millijoules. At 120 Hz repetition rate the average power is about 1 W. The system is optimized for X-ray microscopy in the water window around 2 to 4 nm, and will permit imaging a biological sample in a single subpicosecond pulse. (21 References). |
| title: | A 2-4 nm Linac Coherent Light Source (LCLS) using the SLAC linac |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | H. Winick,K. Bane,R. Boyce,G. Loew,P. Morton,H. Nuhn,J. Paterson,P. Pianetta,T. Raubenheimer,J. Seeman,R. Tatchyn,V. Vylet,C. Pellegrini,J. Rosenzweig,G. Travish,D. Prosnitz,E. Scharlemann,K. Halbach,K. Kim,M. Xie |
| abstract: | We describe the use of the SLAC linac to drive a unique, powerful, short wavelength Linac Coherent Light Source (LCLS). Operating as an FEL, lasing would be achieved in a single pass of a high peak current electron beam through a long undulator by self-amplified spontaneous emission. The main components are a high-brightness rf photocathode electron gun; pulse compressors; about 1/5 of the SLAC linac; and a long undulator with a FODO quadrupole focusing system. Using electrons below 8 GeV, the system would operate at wavelengths down to about 3 nm, producing [right angle bracket]or=10 GW of peak power in sub-ps pulses. At a 120 Hz rate the average power is approximately=1 W. (6 References). |
| title: | A Comparison Between the Performance of Split and Integrated RF Photoinjectors |
| conference: | 1999 Particle Accelerator Conference |
| year: | 1999 |
| authors: | J. Rosenzweig,S. Anderson,X. Ding,L. Serafini |
| abstract: | RF photoinjectors, the present source of choice for production of ultra-high brightness electron beams, have two basic design types: split, in which a short, high gradient rf gun is followed by a a drift and a booster linac, and a lower gradient integrated photoinjector, in which the linac acceleration is connected directly to the gun. The first type is represented at UCLA by the Neptune photoinjector, the second by the newly constructed S-band PWT photoinjector. We examine, through simulation and theory, the relative merits of each type of injector, both from the point of view of the beam physics (ability of the source to produce high currents and low emittances), and of relative technical advantages. |
| title: | A Fast Method to Estimate the Gain of the Microbunch Instability in a Bunch Compressor |
| conference: | 2003 Particle Accelerator Conference |
| year: | 2003 |
| authors: | S. Reiche,J. Rosenzweig |
| abstract: | For the users of the high-brightness radiation sources of free-electron lasers it is necessary to reduce the FEL pulse length to 10 fs and below for time-resolving pump and probe experiments. Although it can be achieved by conventional compression methods for the electron beam or the chirped FEL pulse, the technical realization is demanding. In this presentation we study the impact of undulator wakefields and how their properties can be used to reduced the amplifying part of the bunch to the desired length. Methods of actively controlling the wakefields are presented. |
| title: | A Helical Undulator Wave-guide Inverse Free-Electron Laser |
| conference: | |
| year: | 2004 |
| authors: | J. Rosenzweig,N. Bodzin,P. Frigola,C. Joshi,P. Musumeci,C. Pellegrini,S. Tochitsky,and Travish |
| abstract: | With recent success in high gradient, high-energy gain IFEL experiments at the UCLA Neptune Laboratory, future experiments are now being contemplated. The Neptune IFEL was designed to use a tightly focused, highly diffracting, near-TW peak power 10 micron laser. This choice of laser focusing, driven by power-handling limitations of the optics near the interaction region, led to design and use of a very complex undulator, and to sensitivity to both laser misalignment and focusing errors. As these effects limited the performance of the IFEL experiment, a next generation experiment at Neptune has been studied which avoids the use of a highly diffractive laser beam through use of a waveguide. We discuss here the choice of low-loss waveguide, guided mode characteristics and likely power limitations. We also examine a preferred undulator design, which is chosen to be helical in order to maximize the acceleration achieved for a given power. With the limitations of these laser and undulator choices in mind, we show the expected performance of the IFEL using 1D simulations. Three-dimensional effects are examined, in the context of use of a solenoid for focusing and acceleration enhancement. |
| title: | A High Voltage Extractor with Photocathodes |
| conference: | 1998 European Particle Accelerator Conference |
| year published: | 1999 |
| year authored: | 1998 |
| authors: | G. Travish,D. Giove,P. Michelato,C. Pagani,P. Pierini,L. Serafini,D. Sertore |
| abstract: | We describe a system designed for photocathode testing and beam dynamics studies which is based on a high voltage extractor and a sub–ps drive laser. The system’s distinctive characteristics are the ability to run in the short bunch regime — where the dynamics are not governed by the Child–Langmuir law — and the anticipated availability of both transverse and longitudinal beam diagnostics to determine the full beam distribution. The system consists of a pseudo parallel plate 100 kV DC gun with a removable cathode and a cathode–anode gap of 8 mm, yielding a cathode field of up to 10 MV/m. The drive laser is a Nd:Glass system capable of producing over 200 ?J at 264 nm with a pulse length adjustable from approximately 250 fs to over 1 ps. The goals of the system, described in this paper, are to support ongoing photocathode studies, including measuring high current density extraction from prepared cathodes and investigating the effect of surface variation of the quantum efficiency. Additional studies foreseen include parameterizing the effect of surface variations on the transverse emittance, and exploring beam dynamics such as the short bunch blow out regime which has recently been proposed as a way to produce uniform ellipsoidal charge density distributions[1]. |
| title: | A Linear Collider Based on Nonlinear Plasma Wake-field Acceleration |
| conference: | Summer Study on New Directions for High Energy Physics |
| year published: | 1997 |
| year authored: | 1996 |
| authors: | J. Rosenzweig,N. Barov,E. Colby |
| abstract: | A proposal for a linear collider based on an advanced accelerator scheme, plasma wake-field acceleration in the extremely nonlinear regime is discussed. In this regime, many of the drawbacks associated with preservation of beam quality during acceleration in plasma are mitigated. Experimental progress towards high-gradient acceleration in this scheme is reviewed. We then examine a linear collider based on staging of many modules of plasma wake-field accelerator, all driven by a high average current, pulse compressed, rf photoinjector-fed linac. Issues of beam loading, efficiency, optimized stage length, and power efficiency are discussed. A proof-of-principle experimental test of the staging concept and the Fermilab Test Facility is discussed. |
| title: | A Numerical Method of Calculating the Effective Start-Up Power in a High Gain Free Electron Laser |
| conference: | 18th International Free Electron Laser Conference |
| year published: | 1997 |
| year authored: | 1996 |
| authors: | M. Hogan,G. Travish |
| abstract: | We present a simple model of the startup process in a high gain Free Electron Laser (FEL). The model is used to numerically calculate the power generated within the first gain length of the FEL, which is amplified by the remainder of the undulator. The model takes into account the bandwidth and angular limits imposed by the high-gain process. A brief comparison of the results of this model to an analytic approximation for calculating the start-up power is also given. |
| title: | A PMQ-based, Ultra-short Focal Length, Final Focus System for Next Generation Beam-Radiation and Beam-Plasma Experiments |
| format: | talk |
| year: | 2004 |
| authors: | G. Travish |
| abstract: | Next-generation advanced-accelerators such as the PWFA, and beam-radiation interactions such as inverse-Compton scattering, depend on increased beam-density to achieve superior results. The photoinjector has enabled the production of high-brightness beams that are desirable for experiments with critical dependencies on bunch length and emittance. Along with the production of shorter and lower-emittance beams, comes the need to produce shorter focal-lengths (beta-functions). An approach to creating strong focusing-channels using high field, small-bore permanent-magnet quadrupoles (PMQs) has been followed by the authors. A focusing system using three PMQs, each composed of 16 Nd-Fe-B sectors in a Halbach geometry has been installed in the PLEIADES inverse-Compton experiment. As the magnets are of a fixed field-strength, the focusing system is tuned by adjusting the position of the three magnets along the beamline axis. This presentation covers the details of the focusing system, experimental experience, and implications for future experiments with an emphasis on advanced accelerators. |
| title: | A PMQ-based, Ultra-short Focal Length, Final Focus System for Next Generation Beam-Radiation and Beam-Plasma Experiments |
| conference: | |
| year: | 2004 |
| authors: | G. Travish,P. Frigola,J. Lim,J. Rosenzweig |
| abstract: | Abstract. Next-generation advanced-accelerators such as the PWFA, and beam-radiation interactions such as inverse-Compton scattering, depend on increased beam-density to achieve superior results. The photoinjector has enabled the production of high-brightness beams that are desirable for experiments with critical dependencies on bunch length and emittance. Along with the production of shorter and lower-emittance beams, comes the need to produce shorter focal-lengths (beta-functions). An approach to creating strong focusing-channels using high field, small-bore permanent-magnet quadrupoles (PMQs) has been followed by the authors. A focusing system using three PMQs, each composed of 16 Nd-Fe-B sectors in a Halbach geometry has been installed in the PLEIADES inverse-Compton experiment. As the magnets are of a fixed field-strength, the focusing system is tuned by adjusting the position of the three magnets along the beamline axis. This paper covers the details of the focusing system, experimental experience, and implications for future experiments with an emphasis on advanced accelerators. |
| title: | A Plasma-Assisted High-Brightness X-Ray Source via Inverse Compton Scattering |
| format: | unpublished |
| year: | 2003 |
| authors: | J. Rosenzweig,R. Yoder,G. Travish |
| abstract: |
| title: | A Resonant, THz Slab-Symmetric Dielectric-Based Accelerator |
| conference: | 10th Advanced Accelerator Concepts Workshop |
| year: | 2002 |
| authors: | R. Yoder,J. Rosenzweig |
| abstract: |
| title: | A Resonant, THz Slab-Symmetric Dielectric-Based Accelerator |
| conference: | ICFA Workshop on Physics and Applications of High Brightness Electron Beams |
| year published: | 2003 |
| year authored: | 2002 |
| authors: | R. Yoder,J. Rosenzweig |
| abstract: | Slab-symmetric dielectric-loaded structures, consisting of a vacuum gap between dielectric-lined conducting walls, have become a subject of interest for highgradient acceleration of high-charge beams due to their simplicity, relatively low power density, and advantageous beam dynamics. Such a structure can be resonantly excited by an external power source and is known to strongly suppress transverse wakefields. Motivated by the prospect of a high-power FIR radiation source, currently under construction at UCLA, we investigate a high-gradient slabsymmetric accelerator powered by up to 100 MW of laser power at 340 ?m, with a predicted gradient near 100 MeV/m. Theory and simulation studies of the structure fields and wakes are presented, with an outline of a future experiment. |
| title: | A Simple Calculation of Electron and Lattice Heating in the UCLA RF Photocathode |
| format: | |
| year published: | December 17, 1992 |
| year authored: | 1992 |
| authors: | J. Rosenzweig |
| abstract: | It has been suggested by C. Joshi that the source of pulse lengthening in the electon beam emitted from the UCLA rf photocathode is due to the heating of the conduction electrons in the copper by the laser pulse. The proposed mechanism for continued emission after the end of the laser is thermally enhanced field emission. Simple calculations (see below) indicate that the temperature rise associated with the laser power deposition could be, in the absence of diffusion and coupling to the ions, in excess of 1000 degrees Kelvin, a temperature which could indeed allow emission. In addition, there have been experiments on this films have shown that this elevated termperature can persist for many picoseconds after the laser is no longer on. The purpose of this note is to explore, using a simple model based on the heat equations for the electrons and the ion lattice, and an even more simplified numerical solution of these coupled differential equations, the heating, as well as the diffusion and coupling of this heat, in our cathode. |
| title: | A Slab-Symmetric Dielectric-Loaded Structure for High-Gradient Acceleration at THz |
| conference: | 2003 Particle Accelerator Conference |
| year: | 2003 |
| authors: | R. Yoder,J. Rosenzweig |
| abstract: | We present a design for a slab-symmetric accelerating structure to be resonantly excited at terahertz frequencies. The device, consisting of a vacuum gap between dielectric-lined walls, combines the advantages of a slab geometry (including strong suppression of transverse beam wakefields and low power density) with the existence of a resonant mode having phase synchronism with relativistic electrons. Accelerating fields of hundreds of MeV/m are predicted when the structure is powered by a high-power FIR radiation source in development at UCLA. Simulation of the structure fields is described and compared with theory, and an experimental program is discussed. |
| title: | A Study of Linewidth, Noise and Fluctuations in a FEL Operating in SASE |
| conference: | 15th International Free Electron Laser Conference |
| year published: | 1994 |
| year authored: | 1993 |
| authors: | R. Bonifacio,L. De Salvo,P. Pierini,N. Piovella,C. Pellegrini |
| abstract: | We study the evolution of the FEL radiation intensity and spectrum starting from noise in the electron beam longitudinal distribution. Due to the slippage both the time and frequency structure of the emitted radiation pulse show a very different behavior when the bunch length is much longer than or of the order of the cooperation length l(c). The occurrence of superradiant spikes is discussed. We present analytical and numerical results. |
| title: | A THz radiation driven IFEL as a phaselocked prebuncher for a plasma beat-wave accelerator |
| conference: | International Conference on Lasers 2001 |
| year published: | 2002 |
| year authored: | 2001 |
| authors: | P. Musumeci,S. Tochitsky,C. Clayton,C. Joshi,C. Pellegrini,J. Rosenzweig |
| abstract: | To obtain a high quality electron beam with small energy spread in the laser driven plasma accelerator, the electrons have to be prebunched at the scale of the plasma wavelength. We study the feasibility of an experiment where an inverse free electron laser (IFEL) is used to bunch the electron beam before the injection into a plasma beatwave accelerator. It is suggested to drive the IFEL prebuncher by a THz seed radiation phase-locked to the electromagnetic beatwave through difference frequency generation process in a nonlinear crystal. Design and numerical simulations for this experiment are presented. |
| title: | A diagnostic system to measure SASE-FEL radiation properties along the 4-meter VISA undulator |
| conference: | 21st International Free Electron Laser Conference |
| year published: | 2000 |
| year authored: | 1999 |
| authors: | A. Murokh,E. Johnson,J. Rosenzweig,A. Tremaine |
| abstract: |
| title: | A dielectric-loaded resonant laser accelerator |
| conference: | 6th Advanced Accelerator Concepts Workshop |
| year published: | 1995 |
| year authored: | 1994 |
| authors: | J. Rosenzweig,A. Murokh,C. Pellegrini |
| abstract: | A laser-pumped accelerator utilizing a resonant, periodic, dielectric-loaded structure is proposed. The electromagnetic fields due to a side-injected laser beam impinging on this structure are described in a two-dimensional standing-wave approximation, and analyzed in terms of their suitability for accelerating electrons to ultra-relativistic energies. The longitudinal dynamics of injected electrons in the capture phase of the motion are discussed, as are the first and second order transverse focusing effects inherent in this type of structure. Similarities and differences between this scheme, and conventional as well as advanced accelerators, and practical issues relevant to experimental realization of laser acceleration are examined. (20 References). |
| title: | A fast method to estimate the gain of the microbunch instability in a bunch compressor |
| conference: | 24th International Free Electron Laser Conference |
| year published: | 2003 |
| year authored: | 2002 |
| authors: | S. Reiche,J. Rosenzweig |
| abstract: | To reach high peak currents driving Free-Electron Lasers an initial chirped electron bunch is compressed in a bunch compressor. The interaction of the electron beam with its radiation field can yield a collective instability, which amplifies any initial modulation in the current profile. We present a model, which allows to derive an explicit analytical expression for the gain of the microbunch instability. The results are compared to those of the more complex analytical models. |
| title: | A full energy positron source for the UCLA phi factory |
| conference: | Workshop on Testing CPT and Studying CP Violation at a Phi Factory |
| year published: | 1991 |
| year authored: | 1990 |
| authors: | W. Barletta,C. Pellegrini |
| abstract: | The authors describe a full energy injection system suitable for rapid filling of a compact phi factory with high luminosity. Several novel approaches are suggested to minimize power on the positron target and to allow single bunch injection of electrons. (4 References). |
| title: | A high brightness electron accelerator and its particle beam physics. Experimental program |
| conference: | INFN International School on Electromagnetic Radiation and Particle Beams Acceleration |
| year published: | 1989 |
| year authored: | 1988 |
| authors: | C. Pellegrini |
| abstract: | Reviews the main characteristics of the Accelerator Test Facility (ATF), and gives a short discussion of the experimental program to be carried out with it. This program will utilize the unique possibility offered by the ATF, of providing a high brightness electron bunch, synchronized with high power laser pulses. Part of the program will be based on the study of the interaction between the laser radiation and the electrons, in particular laser acceleration of particle beams, and the nonlinear dynamics of electrons in a strong electromagnetic field. Another part will utilize the high brightness of the electron beam to study the physics of free electron lasers in the high gain regime, with the aim of establishing a basis for the development of FELs in the soft X-ray region. (14 References). |
| title: | A high current superconducting proton linac for an accelerator driven transmutation system |
| conference: | 1997 Particle Accelerator Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | C. Pagani,G. Bellomo,P. Pierini,G. Travish,D. Barni,A. Bosotti,R. Parodi |
| abstract: | High current CW proton linac accelerators have been recently proposed for a number of applications based on the use of a large flux of spallation neutrons. In this context, an R&D program on an accelerator driven system for nuclear waste transmutation has been recently approved in Italy. Our specific task is to develop, together with the national industry, a design of the high energy part of the proton accelerator, along with prototype development for the most critical components. In this paper we present a revised version of the design proposed at Linac'96, using five cell cavities, rather than the original four cells. This modification, together with a new criterion for using the transit time factor curve for non resonant proton velocities, results in a more modular and efficient design. A 1.6 GeV linac, operated at 25 mA, allows to reach 40 MW beam power. The beam power upgrade is achievable using additional couplers per cavity. (5 References). |
| title: | A high energy proton-electron-positron colliding beam system |
| conference: | 8th International Conference on High Energy Accelerators |
| year: | 1971 |
| authors: | C. Pellegrini,J. Rees,B. Richter,M. Schwartz,D. Mohl,A. Sessler |
| abstract: | A system of two intersecting storage tings of gross radius 260 m, one for protons and the other for electrons and positrons, is described. The maximum energy of the stored proton beam is 70 GeV, that of the electron and positron beams 15 GeV; so the center-of-mass energies are 65 GeV for e-p collisions and 30 GeV for e/sup +/-e/sup -/ collisions. The performance of the system is determined by the RF power available for the electron and positron brams and by the incoherent beam-beam limit on transverse beam density. With an available RF power for the beams of 2.7 MW, the system yields design luminosities in the vicinity of 10/sup 32/ cm/sup -2/ sec/sup -1/ in both modes of operation. Some important physics experiments and their yields are discussed. |
| title: | A high luminosity superconducting mini collider for phi meson production and particle beam physics |
| conference: | 1991 Particle Accelerator Conference |
| year: | 1991 |
| authors: | C. Pellegrini,D. Robin,D. Cline,J. Kolonko,C. Anderson,W. Barletta,A. Chargin,M. Cornacchia,G. Dalbacka,K. Halbach,E. Lueng,F. Kimball,D. Madura,L. Patterson |
| abstract: | A 510-MeV electron-positron collider has been proposed at the University of California at Los Angeles to study particle beam physics and phi-meson physics at luminosities larger than 1032 cm/sup -2/s/sup -1/. The collider consists of a single compact superconducting storage ring (SMC), with a bending field of 4 T and a current larger than 1 A. A discussion is presented of the main characteristics of this system and its major technical components: superconducting dipoles and the RF vacuum and injection systems. (6 References). |
| title: | A high-luminosity BB factory linear collider using positron recirculation and recovery |
| journal: | Nuclear Instruments & Methods A |
| vol-pages: | 297-302 |
| year: | 1990 |
| authors: | D. Cline,C. Pellegrini |
| abstract: | The authors describe an asymmetric linear collider BB factory scheme that offers a possible solution to most of the problems encountered in the design of BB factories to operate at the Upsilon (4S) energy. A key feature of this collider is the recirculation and recovery of the positrons and the asymmetric energy of the collider to better achieve the search for CP violation in the B system. (8 References). |
| title: | A linear collider phi factory and beam dynamics test machine |
| conference: | Workshop on CP Violation in Particle Physics and Astrophysics |
| year published: | 1990 |
| year authored: | 1989 |
| authors: | W. Barletta,R. Berg,A. Boden,C. Buchanan,D. Cline,A. Fridman,C. Ho,C. Pellegrini |
| abstract: | The authors present the design of a high luminosity linear collider phi factory. This machine can be used to search for violation of CPT invariance and the study of CP violation ( epsilon '). It can also serve as a test collider to study the feasibility of L > 10(34) cm(-2) sec(-1) BB factory and the beam dynamics of large disruption systems. The machine will be asymmetric in beam energy, thus giving the phi 's a boost. (3 References). |
| title: | A measurement of high gain SASE FEL induced electron beam micro-bunching using coherent transition radiation |
| conference: | 1999 Particle Accelerator Conference |
| year: | 1999 |
| authors: | A. Tremaine,S. Anderson,P. Frigola,M. Hogan,A. Murokh,C. Pellegrini,J. Rosenzweig,D. Nguyen,R. Sheffield |
| abstract: | Coherent transition radiation (CTR) was used to study the longitudinal modulations of an electron beam exiting the UCLA/LANL high gain SASE FEL. The induced longitudinal micro-bunching of the electron beam at the exit of the undulator was measured with a frequency domain technique using the CTR emitted when this beam strikes a thin conducting foil. Formalisms for both CTR and SASE theories are related using the simulation code GINGER in which the SASE FEL gain of the output radiation and the micro-bunching of the electron beam are given. Experimental results from the CTR measurement will show the limit of standard transition radiation theory is being approached and new analysis is needed. (8 References). |
| title: | A method for measuring the FEL radiation power along an undulator |
| conference: | 21st International Free Electron Laser Conference |
| year published: | 2000 |
| year authored: | 1999 |
| authors: | S. Reiche |
| abstract: | A highly desirable measurement in Free Electron Laser (FEL) experiments is the dependency of the radiation power along the undulator. Most designs of undulators prohibit detection of the radiation power within the undulator or extracting the electron beam at arbitrary positions. Transport of both, the radiation field and the electron beam, through the entire undulator, and thus an ongoing FEL interaction, is unavoidable. If there are many correction magnets distributed along the beam pipe, one can think of exciting a large orbit distortion downstream from any of these correctors. For a gain length comparable to or larger than the beta function this excitation of a coherent betatron oscillation might degrade the FEL amplification to a level, for which the radiation power does not further grow over the remaining length of the undulator. This paper presents the efficiency of this method for the parameters of the VUV FEL at the TESLA Test Facility. |
| title: | A microwiggler free-electron laser at the Brookhaven Accelerator Test Facility |
| conference: | 11th International Free Electron Laser Conference |
| year published: | 1990 |
| year authored: | 1989 |
| authors: | K. Batchelor,I. Ben-Zvi,R. Fernow,J. Gallardo,H. Kirk,C. Pellegrini,A. van Steenbergen,A. Bhowmik |
| abstract: | The authors report the design and status of an FEL experiment at the Brookhaven National Laboratory Accelerator Test Facility. A 50 MeV high-brightness electron beam will be utilized for an oscillator experiment in the visible-wavelength region. The microwiggler to be used is a superferric planar undulator with a 0.88 cm period, 60 cm length and K=0.35. The optical cavity is a 368 cm long stable resonator with broadband dielectric coated mirrors. (8 References). |
| title: | A millimeter wave FEL driven by a photocathode RF linac |
| conference: | 15th International Free Electron Laser Conference |
| year published: | 1994 |
| year authored: | 1993 |
| authors: | R. Zhang,C. Pellegrini,J. Rosenzweig,G. LeSage,F. Hartemann,D. McDermott,C. Joshi,N. Luhmann,P. Pierini,L. de Salvo,R. Bonifacio |
| abstract: | We present the design of a millimeter wave FEL based on the UCLA photocathode RF linac. The linac energy can be varied between 5 and 18 MeV. The electron pulse duration is 2 ps FWHM, with a peak current exceeding 150 A. The FEL is designed to operate in the high-gain Compton regime, controlling the slippage with the propagating radiation in a waveguide. The design permits the exploration of the basic FEL physics in this regime, including the exploration of saturation and lethargy in the superradiant and steady state regime. (15 References). |
| title: | A new method for pumping an optical klystron |
| conference: | International Workshop on Coherent and Collective Properties in the Interaction of Relativistic Electrons and Electromagnetic Radiation |
| year published: | 1985 |
| year authored: | 1984 |
| authors: | G. Vignola,R. Freeman,B. Kincaid,C. Pellegrini,A. Luccio,J. Murphy,J. Galayda,A. van Steenbergen |
| abstract: | A novel method of operation for a transverse optical klystron (TOK) is proposed. The TOK is a device in which a relativistic electron beam produces tunable coherent radiation at short wavelengths by interacting with a powerful external laser and an undulator field. The authors show that, by selecting the external laser wavelength to be one of the harmonics in the undulator radiation spectrum, excellent output at short wavelengths can be realized with significantly reduced performance requirements for the undulator magnet and the storage ring providing the electron beam. (10 References). |
| title: | A permanent-magnet focused X-band photoinjector |
| conference: | 1999 Particle Accelerator Conference |
| year: | 1999 |
| authors: | D. Yu,D. Newsham,P. Wilson,J. Zeng,J. Rosenzweig,X. Ding,F. Hartemann,E. Landahl |
| abstract: | A Plane-Wave-Transformer (PWT), integrated photoinjector operating at an X-band frequency (8.547GHz) is being developed by DULY Research Inc. in a DOE SBIR project, in collaboration with UCLA and UCD/ILSA. Upward frequency scaling from an S-band PWT photoinjector would result in a compact photoinjector with unprecedented brightness. Challenging technological innovations are required at X-band. In particular, water cooling capacity, mechanical support strength, and materials properties do not scale linearly with frequency. Instead of using large solenoids, we have successfully designed the required focusing for an X-band PWT using a compact, permanent magnet system. Also described in this paper is a system design of the X-band photoinjector, including the RF system and the cooling/support of the PWT structure. |
| title: | A plane-wave-transformer photoelectron linac |
| conference: | 1997 Particle Accelerator Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | D. Yu,T. Lee,S. Rajagopalan,J. Chen,C. Pellegrini,J. Rosenzweig,X. Ding |
| abstract: | We develop a novel photoelectron linear accelerator using a plane wave transformer (PWT) design. In this design, the input RF power is coupled to the accelerating cavities via a large concentric manifold cavity. The scheme makes possible very strong coupling between the accelerating cells, and relaxes manufacturing tolerances. The compact photoelectron linac integrates a photocathode directly into a PWT linac structure, and eliminates the drift space between a photoinjector and the linac which would otherwise lengthen the electron bunches. Using an emittance compensation scheme, the PWT photoelectron linac produces a high-brightness beam. We have demonstrated by simulations the feasibility of a 20 MeV PWT photoelectron linac design with a set of eleven iris-loaded disks suspended and cooled by four water tubes inside a large cylindrical tank. (5 References). |
| title: | A plasma klystron for generating ultra-short electron bunches |
| conference: | Workshop on Second Generation Plasma Accelerators |
| year published: | 1996 |
| year authored: | 1995 |
| authors: | T. Katsouleas,C. Clayton,L. Serafini,C. Pellegrini,C. Joshi,J. Dawson,P. Castellano |
| abstract: | A technique for producing ultra-short electron bunches (e,g., less than or equal to 100 fs) from a continuous electron beam using a short plasma wave section and a drift space is explored. The bunches are a fraction of a plasma wavelength long and are spaced by a plasma wavelength, making them of interest for injection into plasma accelerators or for driving a klystron-like structure to produce infrared radiation. |
| title: | A proposed dielectric-loaded resonant laser accelerator |
| journal: | Physical Review Letters |
| vol-pages: | 2467-70 |
| year: | 1995 |
| authors: | J. Rosenzweig,A. Murokh,C. Pellegrini |
| abstract: | A laser-pumped accelerator utilizing a resonant, periodic, dielectric structure is proposed. The electromagnetic fields due to a side-injected laser beam impinging on this structure are calculated in a two-dimensional standing-wave approximation, leading to an estimated accelerating field in excess of 1 GV/m for accessible experimental parameters. The longitudinal dynamics of injected electrons in the device are discussed, as are the first- and second-order transverse focusing effects inherent to this structure. Similarities and differences between this scheme and conventional and other advanced accelerators are examined. (15 References). |
| title: | A study for a 6 GeV undulator based synchrotron radiation source |
| conference: | 1985 Particle Accelerator Conference |
| year: | 1985 |
| authors: | G. Vignola,M. Barton,R. Blumberg,J. Galayda,S. Krinsky,A. Luccio,C. Pellegrini,A. van Steenbergen,J. Wang |
| abstract: | A partial study for a 6 GeV undulator based synchrotron radiation source for production of high brightness undulator radiation, in the angstrom region, is presented. The basic lattice adopted for the storage ring is a hybrid FODO Chasman-Green lattice, making use of gradient in the dipoles. The e beam current limits and the injection parameters are discussed. (8 References). |
| title: | A study on the choice of parameters for a high energy electron ring accelerator |
| journal: | Particle Accelerators |
| vol-pages: | 45-56 |
| year: | 1971 |
| authors: | C. Bovet,C. Pellegrini |
| abstract: | The production of high energy (multi-GeV) proton beams by an electron ring accelerator is considered. Both the final energy and intensity of the proton beam depend on the choice of parameters for the electron ring. Possible sets of parameters, consistent with all the known requirements of ring stability, and which optimize the energy and (or) the intensity of the proton beam, are presented. (19 References). |
| title: | A study on the conditions required for the transverse stability of a coasting beam in proton storage rings |
| journal: | Particle Accelerators |
| vol-pages: | 147-68 |
| year: | 1982 |
| authors: | M. Cornacchia,C. Pellegrini |
| abstract: | A theory is developed that allows calculation of the threshold current of a coasting beam in a circular accelerator or storage ring for an arbitrary frequency versus momentum curve. This theory is applied to the simple case of a parabolic term in the curve, for which an analytical solution of the stability problem is obtained. The general case of an arbitrary frequency distribution is then solved numerically, and the solution used to study the stability of a coasting beam in a high-energy proton storage ring like ISABELLE during the stacking process and for a full-intensity beam. This is done for different momentum distribution curves and includes the effect of the nonlinear space-charge term and of up to sixteen independent magnetic multipoles. The algorithm allows calculation of both the number and the strength of the magnetic multipoles needed to provide a stable beam of the desired current. (8 References). |
| title: | A two stage IFEL accelerator |
| conference: | APS April Meeting |
| year: | 2000 |
| authors: | P. Musumeci,C. Pellegrini |
| abstract: | We present a two stage Inverse Free Electron Laser accelerator proposed for construction at the UCLA Neptune Lab. Proof-of-principle experiments on the IFEL scheme have been carried out succesfully. This experiment is intended to achieve a 100 Mev energy gain, staging two IFEL modules. It will use the 16 Mev electron beam produced by the Neptune linac, the 1 TW MARS CO2 laser and two different tapered undulators. The problem of refocusing both laser and electron beam is analyzed in detail. A preliminary beamline layout and numerical simulations are presented. |
| title: | Acceleration of Injected Electrons In A Laser Beatwave Experiment |
| conference: | 2003 Particle Accelerator Conference |
| year: | 2003 |
| authors: | S. Tochitsky,R. Narang,C. Filip,P. Musumeci,C. Clayton,R. Yoder,K. Marsh,J. Rosenzweig,C. Pellegrini,C. Joshi |
| abstract: | Plasma-based accelerators of particles are of great interest because plasmas can sustain very strong electric fields. They are utilizing a relativistic plasma wave with a phase velocity close to the speed of light driven by a high-power laser beam. The Neptune Laboratory at UCLA is being used for plasma beatwave acceleration of injected electrons. Here, a two-wavelength laser pulse (frequencies w1,w2) resonantly drives a longitudinal electron plasma wave of frequency equal to w1-w2, providing a field strength of GeV/m and, therefore, accelerates an injected electron beam at this very high gradient. A 10 ps beam of 12 MeV electrons is loaded in a 3-cm long plasma beatwave accelerator driven by a TW CO2 laser pulse. At the resonance condition, the electrons have been accelerated to 50 MeV with a gradient of ~1.3 GeV/m. It is shown that for large volume diffraction limited plasmas, when efficiency of the plasma wave excitation is restricted by ionization-induced refraction, acceleration of electrons is enhanced significantly by using asymmetric (fast front and slow fall) long pulses. 2D PIC simulations revealed that guiding of the laser pulse in a ponderomotive, self-induced ion channel, formed ~200 ps after the field ionization, allows compensation for the ionization-induced defocusing and efficient driving of the beatwave over the entire length. |
| title: | Accelerator and Charged Particle Beam Physics at UCLA |
| format: | unpublished |
| year published: | March 2002 |
| year authored: | 2002 |
| authors: | J. Rosenzweig |
| abstract: | Outline: What do we do? Who is involved What is current highlights of the research and education programs? Where are the future opportunities |
| title: | Adjustable, short focal length permanent-magnet quadrupole based electron beam final focus system |
| journal: | Physical Review Special Topics - Accelerators and Beams |
| vol-pages: | 8:072401 |
| year: | 2005 |
| authors: | J. Lim,P. Frigola,G. Travish,J. Rosenzweig,S. Anderson,W. Brown,J. Jacob,C. Robbins,A. Tremaine |
| abstract: | Advanced high-brightness beam applicaitons such as inverse-Compton scattering (ICS) depend on achieving of ultra-small spot sizes in high current beams. Modern injectors and compressors enable the production of high-brightness beams having needed short bunch lengths and small emittances. Along with these beam properties comes the need to produce tighter foci, using stronger, shorter focal length optics. An approach to creating such strong focusing-systems using high field, small-bore permanent-magnet quadrupoles (PMQs) is reported here. A final focus system employing three PMQs, each composed of 16 neodymium iron boride sectors in a Halbach geometry has been installed in the PLEIADES ICS experiment. The field gradient in these PMQs is 560 T/m, the highest ever reported in a magnetic optics system. As the magnets are of a fixed field-strength, the focusing system is tuned by adjusting the position of the three magnets along the beamline axis, in analogy to familiar camera optics. This paper discusses the details of the focusing system, simulation, design, fabrication and experimental procedure in creating ultra-small beams at PLEIADES. |
| title: | An Adjustable Permanent Magnet Quadrupole Final Focus System for Low Energy Experiments |
| conference: | 2003 Particle Accelerator Conference |
| year: | 2003 |
| authors: | J. Lim,P. Frigola,J. Rosenzweig,S. Telfer,G. Travish,W. Brown,A. Tremaine |
| abstract: | The final focus system for the Thomson X-ray scattering experiment termed PLEIADES (Picosecond Laser-Electron InterAction for Dynamic Evaluation of Structures) at LLNL demands ultra-high field gradient quadrupoles in order to focus initially small beams to 10-20 micron spot sizes. This scheme circumvents limitations due to chromatic aberrations and space-charge effects in this relatively low energy (<100 Mev) system. The final focus scheme is based on an ultra-high gradient (300T/m) quadrupole which employs the Halbach 16-piece, permanent magnet design. Use of this optimized goemetry, NdFeB material, and a small (4 mm) bore allows the desired field gradient, and few cm focal length, to be achieved. The adjustability of the focusing system is obtained by changing the relative longitudinal positions of sub-component focusing and defocusing magnets on precision movers. We present the results of RADIA 3D design simulations, and measurement of prototype magnets. We also discuss the results of beam dynamics simulations of the PLEIADES system using both envelope and tracking codes. |
| title: | An Inverse Compton Scattering Radiation Source via Self-Guiding in a Plasma |
| conference: | |
| year: | 2006 |
| authors: | R. Yoder,J. Rosenzweig |
| abstract: | In an inverse-Compton scattering source, in which a relativistic electron beam collides with a high-power laser pulse, the x-ray flux produced is proportional to the brightness of the two beams and the size of their overlap region in three-dimensional space. In vacuum, this overlap is limited by the diffraction of the two beams, but the diffraction limit can be overcome by confining both beams in a plasma guiding channel. A dense, bunched electron beam injected into an underdense plasma will self-guide via ``blowout,'' in which the beam head creates a focusing ion channel through which the body of the beam is guided; this same channel can also guides a counterpropagating laser beam. Constraints include the need for long laser wavelength (1 to 10 µm) and high beam densities. We present a possible configuration for a gamma-ray source using 180° Compton scattering in a uniform plasma, including 2D simulation results. Estimated photon yields are up to a factor of 5 larger than in vacuum scattering, with production of nearly 1010 photons per nanocoulomb of electron beam charge. |
| title: | An Optimal Design for a THz Dielectric-Loaded Slab-Symmetric Accelerator |
| conference: | |
| year: | 2004 |
| authors: | R. Yoder,J. Rosenzweig |
| abstract: | A slab-symmetric dielectric-loaded accelerator structure, consisting of a vacuum gap between dielectric-lined conducting walls, is analyzed theoretically and computationally. The device is to be resonantly excited by an external laser source of wavelength 340 µm. Analytical results for infinite and finite-width geometries are summarized, and 2D electromagnetic simulation is used to demonstrate the time-dependent filling of the structure from the external source. The resonant accelerating fields, which are nearly constant along the short transverse direction, are found to have between 10 and 15 times the amplitude of the driving radiation, with only a small (< 10%) admixture of other non-accelerating modes. Field gradients are near 100 MV/m when the structure is driven with 100 MW of terahertz power. The resonance is highly dependent on the geometry of the slots used to couple radiation into the structure, with effects on the overall Q-factor, frequency detuning, and field pattern. Possible manufacturing methods are discussed, along with an all-dielectric version of the design that would allow scaling of the structure to a wavelength of 10 µm. |
| title: | An Optimized Slab-Symmetric Dielectric-Based Laser Accelerator Structure |
| conference: | 8th Advanced Accelerator Concepts Workshop |
| year published: | 1999 |
| year authored: | 1998 |
| authors: | J. Rosenzweig,P. Schoessow |
| abstract: | A slab-symmetric, partially dielectric filled, laser excited structure which may be used to accelerate charged particles is analyzed theoretically and computationally. The fields associated with the accelerating mode are calculated, as are aspects of the resonant filling and impedance matching of the structure to the exciting laser. It is shown through computer simulation that the accelerating mode in this structure can be excited resonantly and with large quality factor Q. Practical aspects of implementing this structure as an accelerator are discussed. (7 References). |
| title: | An Ultra-High Gradient Cerenkov Wakefield Acceleration Experiment at SLAC FFTB |
| conference: | |
| year: | 2004 |
| authors: | J.B.Rosenzweig J.B.Rosenzweig,S. Hoover,M.J Hogan,P. Muggli,M. Thompson,G. Travish,R. Yoder |
| abstract: | The creation of ultra-high current, ultra-short pulse beams (Q=3 nC, ! "z= 20 µm) at the SLAC FFTB has opened the way for very high gradient plasma wakefield acceleration experiments. We study here the use of these beams in a proposed Cerenkov wakefield experiment, where one may excite electromagnetic wakes in a simple dielectric tube with inner diameter of few100 microns that exceed the GV/m level. We discuss the scaling of the fields with design geometric design parameters, and choice of dielectric. We also examine measurable aspects of the experiment, such as the total coherent Cerenkov radiation energy one may collect, and the expected aspects of dielectric breakdown at high fields. |
| title: | An Ultra-High Gradient Cerenkov Wakefield Acceleration Experiment at SLAC FFTB |
| conference: | |
| year: | 2004 |
| authors: | J.B Rosenzweig,S. Hoover,M.J Hogan,P. Muggli,M. Thompson,G. Travish,R. Yoder |
| abstract: | The creation of ultra-high current, ultra-short pulse beams (Q=3 nC, ) at the SLAC FFTB has opened the way for very high gradient plasma wakefield acceleration experiments. We study here the use of these beams in a proposed Cerenkov wakefield experiment, where one may excite electromagnetic wakes in a simple dielectric tube with inner diameter of few100 microns that exceed the GV/m level. We discuss the scaling of the fields with design geometric design parameters, and choice of dielectric. We also examine measurable aspects of the experiment, such as the total coherent Cerenkov radiation energy one may collect, and the expected aspects of dielectric breakdown at high fields. |
| title: | An X-ray transition radiation beam profile detector for the LCLS |
| conference: | 1998 ICFA Workshop on Nonlinear and Collective Phenomena in Beam Physics |
| year published: | 1999 |
| year authored: | 1998 |
| authors: | S. Monteiro,C. Pellegrini |
| abstract: | We discuss the characteristics of a transverse beam profile detector for a high energy charged particle accelerator, and propose a candidate detector based on transition radiation in the X-ray region of the spectrum. The detector is useful for low emittance, high energy beams, for example, the LCLS electron beam. We expect that it can resolve spatial details as small as a few microns. The advantages of this method over previous ones are that the measurements are linear with the beam density and the results are a point by point map of the beam density. (14 References). |
| title: | An adjustable short-focal length, high-gradient PMQ electron-beam final-focus system for the PLEIADES ultra-fast x-ray Thomson source |
| format: | thesis |
| year: | |
| authors: | Jae Lim |
| abstract: | In the span of a 100 year since the discovery of first x-rays by Roentgen that won him the ¯rst Nobel prize in physics, several types of radiation sources have been developed. Currently, radiations at extremely short wavelengths have only been accessed at synchrotron radiation sources. However, the current 3rd generation synchrotron sources can only produce x-rays of energy up to 60 keV and pulse lengths of several picoseconds long. But needs for shorter wavelength and shorter pulse duration radiations demanded by scientists to understand the nature of matter at atomic/molecular scale initiated the new scienti¯c research for the production of sub-picosecond, hard x-rays. At the Lawrence Livermore National Laboratory, a Thomson x-ray source in the backscattering mode {a head-on collision between a high intensity Ti:Sapphire Chirped Pulse Amplification laser and a relativistic electron beam { called the PLEIADES (Picosecond Laser-Electron Inter-Action for the Dynamical Evaluation of Structures) laboratory has been developed. Early works demonstrated the production of quasi-monochromatic, femto-second long, hard x-rays. Initially reported x-ray flux was in the low range of 10^5 photons per shot. During the early stage of PLEIADES experiments, 15 T/m electromagnet final focusing quadrupoles (in a triplet lattice con¯guration) were employed to focus the beam to a 40-50 ¹m spot-size. A larger focal spot-size beam has a low-density of electron particles available at the interaction with incident photons, which leads to a low scattering probability. The current dissertation shows that by employing a 560 T/m PMQ (Permanent-Magnet Quadrupole) ¯nal focus system, an electron beam as small as 10-20 ¹m can be achieved. The implementation of this final focus system demonstrated the improvement of the total x-ray flux by two orders of magnitude. The PMQ ¯nal focus system also produced small electron beams consistently over 30-100 MeV electron beam energy, which enabled the production of x-ray energy over 40-140 keV. In this dissertation, the PLEIADES Thomson x-ray facility will be described in detail includes the 100 MeV linac and the FALCON laser system. Later, we will discuss the design, construction and implementation of the PMQ final focus system in the beamline. The measurement of electron beam parameters before and after the final focus system will be presented. The beam measurements at the interaction region were accomplished with the use of both OTR (Optical Transition Radiation) imaged by a CCD camera and the fast streak camera for respective spatial and temporal alignments. The theoretical analysis in real beam" effects and spacetime beam jitter e®ects will be given to help understand the observations. A 3D simulation tool developed for x-ray data analysis was used to provide direct comparisons with the x-ray °ux, spectrum distribution and transverse x-ray profile. |
| title: | An injector-prebuncher for a plasma electron accelerator |
| conference: | 1995 Particle Accelerator Conference |
| year: | 1995 |
| authors: | M. Lampel,C. Pellegrini,R. Zhang,C. Joshi,W. Fawley |
| abstract: | Optimum operation of a plasma beat-wave or wakefield accelerator requires an injected beam consisting of a train of electron bunches separated by the plasma wavelength, with each bunch in the train having a length much shorter than the plasma wavelength, and the capability of controlling the relative phase of the electron bunches and plasma wave. The typical plasma wavelength is about 0.1 mm, requiring a bunch length of about 10 to 20 mu m, which is difficult to achieve with conventional RF based injectors. In this paper we describe an electron accelerator-buncher system based on a photoinjector and an FEL, which can satisfy the plasma accelerator requirements. (4 References). |
| title: | An inverse free electron laser driven linear collider electron-positron B-factory |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | N. Barov,C. Pellegrini,J. Sandweiss |
| abstract: | We discuss an electron-positron linear collider B-Factory using Inverse Free Electron Lasers (IFEL) to accelerate the beams. The requirements on luminosity, larger than 10/sup 33/ cm/sup -2/ s/sup -1/, and energy spread of a B Factory introduce stringent conditions on the accelerator and the interaction region. We study the longitudinal dynamics through the IFEL, the efficiency of the acceleration process, and the ratio of particles which become accelerated, and fall within the resonance. The device is found to perform well in the presence of large variations in the laser field intensity over the beam. We also discuss the laser system powering the IFEL, and some of the system tolerances. (7 References). |
| title: | An undulator with nonadiabatic tapering for the IFEL project |
| conference: | 23rd International Free Electron Laser Conference |
| year published: | 2002 |
| year authored: | 2001 |
| authors: | A. Varfolomeev,S. Tolmachev,T. Yarovoi,P. Musumeci,C. Pellegrini,J. Rosenzweig |
| abstract: | We describe the design of a planar undulator with unusually strong tapering, for the inverse FEL experiment (on the IFEL experiment at the UCLA Neptune Lab. Presented at the 2001 Particle Accelerator Conference, June 18-22, 2001, Chicago, Illinois) to be carried out in Neptune Lab. (Nucl. Instr. and Meth. A 410 (1998) 437) at UCLA. A powerful TW CO_2 laser will be used to accelerate electrons up to 50-60 MeV in 50 cm long undulator. A strong undulator tapering is needed because of the short Rayleigh length of the laser beam. Both the magnetic field and the undulator period are tapered to provide synchronicity of the laser beam interaction with a captured electron bunch along the whole undulator length. The most critical part of the undulator is the region near the laser focus. The main characteristics of the IFEL, such as the percentage of trapped electrons, energy of accelerated electrons and sensitivity to the laser focus transverse position, are given. The general principles of the design of this undulator construction can also be useful for high efficiency FEL amplifiers of intense laser modes. |
| title: | Analogies Between Charged Particle Beams and Photon Beams: Simple Methods for Laboratory Use |
| format: | unpublished |
| year published: | October 25, 1991 |
| year authored: | 1991 |
| authors: | J. Rosenzweig |
| abstract: |
| title: | Analysis of the Evolution of Classical Distribution Functions Using Quantum Methods |
| conference: | |
| year: | 1998 |
| authors: | J. Rosenzweig |
| abstract: |
| title: | Analytical model for emittance compensation in RF photo-injectors |
| conference: | 1995 Particle Accelerator Conference |
| year: | 1995 |
| authors: | L. Serafini,J. Rosenzweig |
| abstract: | In this paper we present a new model to represent analytically the transverse beam dynamics in RF photo-injectors. It consists basically of an enhanced Kim's model, with incorporation of RF ponderomotive focusing effects, external magnetic focusing and a perturbative treatment of space charge along the beam envelope. Applying the resulting formulas it is possible to predict with high accuracy the transverse beam envelope behaviour in a multi-cell RF gun, as well as the operating conditions to achieve space charge emittance compensation according to Carlsten's scheme. The agreement with sophisticated numerical simulations is really quite satisfactory, as well as the match with experimental measurements of the predicted operating range for emittance compensation. (7 References). |
| title: | Applications of short bunches |
| conference: | Micro Bunches Workshop |
| year published: | 1996 |
| year authored: | 1995 |
| authors: | C. Pellegrini |
| abstract: | We discuss the applications of short, high brightness, high intensity electron bunches to colliders, generators of X-ray radiation like FELs and Compton backscattering, and high frequency linear accelerators like laser or plasma wakefield accelerators. (8 References). |
| title: | Argonne plasma wake-field acceleration experiments |
| conference: | 1989 Workshop on Advanced Accelerator Concepts |
| year: | 1989 |
| authors: | J. Rosenzweig,B. Cole,W. Gai,R. Konecny,J. Norem,P. Schoessow,J. Simpson |
| abstract: | Four years after the initial proposal of the Plasma Wake-field Accelerator (PWFA), it continues to be the object of much investigation, due to the promise of the ultra-high accelerating gradients that can exist in relativistic plasma waves driven in the wake of charged particle beams. These wake-fields are of interest both in the laboratory, for acceleration and focusing of electrons and positrons in future linear colliders, and in nature as a possible cosmic ray acceleration mechanism. The authors review the recent experimental advances made in PWFA research at Argonne National Laboratory. (25 References). |
| title: | Asymmetric emittance RF photocathode source for linear collider applications |
| conference: | 3rd Advanced Accelerator Concepts Workshop |
| year published: | 1993 |
| year authored: | 1992 |
| authors: | J. Rosenzweig,J. Smolin |
| abstract: | Laser driven RF photocathodes represent a recent advance in high-brightness electron beam sources. The authors investigate here a variation on these devices, that obtained by using a ribbon laser pulse to illuminate the cathode, yielding a flat beam (sigma_x >> sigma_y) which has asymmetric emittances at the cathode proportional to the beam size each transverse dimension. The flat-beam geometry mitigates space charge forces which lead to intensity dependent transverse and longitudinal emittance growth, thus limiting the beam brightness. The fundamental limit on achievable emittance and brightness is set by the transverse momentum distribution and peak current density of the photo-electrons (photon energy and cathode material dependent effects) and appears to allow, taking into account space charge and RF effects, normalized emittances epsilon_x <1x10(-4) m-rad and epsilon_y < 10(-6) m-rad, with Q = 5 nC and sigma_z = 1 mm. These source emittances are adequate for superconducting linear collider applications, and could preclude the use of a damping ring for the electrons in these schemes. |
| title: | BPM Revisit: Summary of the Previous Test Results |
| format: | unpublished |
| year: | 1993 |
| authors: | R. Zhang,P. Davis,G. Hairapetian,S. Hartman,S. Park |
| abstract: |
| title: | Beam Break-Up in a KEK TBA |
| format: | tech note |
| year: | 1989 |
| authors: | D. Whittum,G. Travish |
| abstract: |
| title: | Beam Dynamics in a Hybrid Standing Wave-Traveling Wave Photoinjector |
| conference: | |
| year: | 2006 |
| authors: | J.B Rosenzweig,D. Alesini,A.Boni A.Boni,M. Ferrario,L. Ficcadenti,A.Fukusawa A.Fukusawa,A.Mostacci A.Mostacci,B.O’Shea B.O’Shea,L. Palumbo,B.Spataro B.Spataro,V.Fusco V.Fusco |
| abstract: | We discuss the dynamics of of a photoinjector beam in a hybrid traveling wave-standing wave photoinjector. With the field profile deduced from electromagnetic simulations, it is seen that the acceleration program induces strong velocity bunching. The beam dynamics in this scenario are explored using UCLA PARMELA. With a solenoid field overlaid on the TW section one may control emittance oscillations during bunching and acceleration. It is seen that the S-band device currently under development at UCLA may produce a 1 nC, 21 MeV, 100 micron rms pulse length beam, with emittance of 3 mm-mrad. Applications of this beam for creating coherent radiation are discussed. |
| title: | Beam Shaping and Compression Scheme for the UCLA Neptune Laboratory |
| conference: | 2003 Particle Accelerator Conference |
| year: | 2003 |
| authors: | R. England,P. Musumeci,R. Yoder,J. Rosenzweig |
| abstract: | We have recently added a dispersionless translating section to the UCLA Neptune linear accelerator beamline. This new section of beamline will serve as a venue for beam shaping and compression experiments using the 14MeV electron beam produced by the UCLA Neptune PWT linac and newly installed photoinjector. An examination of the first and second-order optics indicates that when certain nonlinear effects are minimized through the use of sextupole magnets, the longitudinal dispersion is dominated by a negative R56 which, for an appropriately chirped initial beam, can be used to create a ramped beam of a few picosecond duration that would be ideal for driving large amplitude wake fields in a plasma and producing high transformer ratios. The beamline is now in operation. Preliminary data indicate that the beamline optics are well-predicted by simulation and that sextupoles can be used successfully to eliminate nonlinear horizontal dispersion. Future experiments are planned for measuring beam compression (using CTR autocorrelation) and doing longitudinal phase space tomography (using a transverse deflecting cavity). |
| title: | Beam amplitude behavior upon crossing a linear coupling resonance with damping in one dimension |
| journal: | IEEE Transactions on Nuclear Science |
| vol-pages: | 176-9 |
| year: | 1969 |
| authors: | M. Lee,E. Courant,C. Pellegrini,A. Sessler |
| abstract: | A study has been conducted to investigate theoretically the effects of vertical damping on the betatron oscillations for particles passing through a resonance. This report describes a calculation for a single-particle model and for the case of the upsilon /sub 1/+ upsilon /sub 2/=1 resonance. |
| title: | Beam break-up in the two-beam accelerator |
| conference: | 1989 Particle Accelerator Conference |
| year: | 1989 |
| authors: | D. Whittum,G. Travish,A. Sessler,G. Craig,J. DeFord |
| abstract: | Beam breakup (BBU) in the drive beam of a two-beam accelerator (TBA) using transverse wakes calculated by the AMOS code was studied numerically. Only cumulative BBU due to the wake of the linear induction accelerator cavities is considered. Growth lengths on the order of approximately 100 m are found for typical parameters. It is concluded that these growth lengths are acceptable for a future TBA. (14 References). |
| title: | Beam collimation for LCLS beam emittance and charge control |
| conference: | 19th ICFA Beam Dynamics Workshop on Physics of, and Science with, the X-Ray Free-Electron Laser |
| year published: | 2001 |
| year authored: | 2000 |
| authors: | C. Schroeder,H. Nuhn,C. Pellegrini |
| abstract: | We describe an electron beam collimator for the linac coherent light source (LCLS). The collimator reduces both the transverse emittance and the total charge of the electron beam. Beam optics are designed to increase the beam spot size for collimation. The impedance of the collimator is calculated, and the wakefield induced emittance growth is determined. (12 References). |
| title: | Beam compression experiments using the UCLA/ATF compressor |
| conference: | |
| year: | 2006 |
| authors: | J.B ROSENZWEIG,M. DUNNING,E. HEMSING,G. ANDONIAN,A.M COOK,A. MUROKH,S. REICHE,D. SCHILLER,M. BABZIEN,K. KUSCHE,V. YAKIMENKO,L. PALUMBO,C. VICARIO |
| abstract: | We review recent experimental results from the BNL ATF using the compressor built by UCLA. The measurements discussed include: first observation of short wavelength coherent edge radiation angular/wavelength spectrum and spectrum, sub-100 fsec pulse-length coherent transition autocorrelation measurements, and longitudinal and transverse phase space distortions. Extension of these measurements, as well as those which can be made possible by a new X-band traveling wave deflector being developed in an industrial collaboration, are examined. |
| title: | Beam dynamics in an integrated plane wave transformer photoinjector at S and X-band |
| conference: | 1997 Particle Accelerator Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | J. Rosenzweig,X. Ding,D. Palmer,C. Pellegrini,L. Serafini,D. Yu |
| abstract: | The beam dynamics of an integrated S-band RF photoinjector based on the plane wave transformer (PWT) concept, proposed as part of an SBIR collaboration between UCLA and DULY Research, are studied. The design, which calls for an 11.5 cell structure run at a peak accelerating field of 60 MV/m and uses a compact solenoid around the initial 2.5 cells, is based on a recently developed theory of emittance compensation. It calls for matching the beam onto a generalized equilibrium envelope, which produces a beam which diminishes in transverse size monotonically with acceleration. This condition minimizes the emittance, which is 1 mm-rad at Q=1 nC. This design is also scaled to produce nearly identical performance at X-band, giving an injector appropriate to running an FEL at the SLAC NLCTA. These designs are insensitive to RF emittance increase, allowing a wide choice of injection phase, and the option to compress the emitted pulse. (8 References). |
| title: | Beam extraction studies at 900 GeV using a channeling crystal |
| journal: | Physical Review Special Topics-Accelerators & Beams |
| vol-pages: | 043501 |
| year: | 2002 |
| authors: | R. Carrigan,D. Chen,G. Jackson,N. Mokhov,C. Murphy,S. Baker,S. Bogacz,D. Cline,S. Ramachandran,J. Rhoades,J. Rosenzweig,A. Asseev,R. Biryukov,A. Taratin,J. Ellison,A. Khanzadeev,T. Prokofieva,V. Samsonov,G. Solodov,B. Newberger,E. Tsyganov,H. Shih,W. Gabella,B. Cox,V. Golovatyuk,A. McManus |
| abstract: | Luminosity-driven channeling extraction has been observed for the first time in a 900 GeV study at the Fermilab Tevatron. This experiment, Fermilab E853, demonstrated that useful TeV level beams can be extracted from a superconducting accelerator during high luminosity collider operations without unduly affecting the background at the collider detectors. Multipass extraction was found to increase the efficiency of the process significantly. The beam extraction efficiency was about 25%. Studies of time dependent effects found that the turn-to-turn structure was governed mainly by accelerator beam dynamics. Based on the results of this experiment, it is feasible to construct a parasitic 5?10 MHz proton beam from the Tevatron collider. |
| title: | Beam optics of a self-focusing plasma lens |
| journal: | Physical Review D |
| vol-pages: | 2039-45 |
| year: | 1989 |
| authors: | J. Rosenzweig,P. Chen |
| abstract: | In this paper the authors analyze the optics of a high-energy beam which is focused by its own wakefields in a plasma. They calculate the effects of lens aberrations on the focusing strength of the lens and on the dilution of the beam's phase space. From this they derive the minimum spot size achievable using a bi-Gaussian beam and, after inclusion of the beam-beam pinch effect, the luminosity enhancement that can be gained in principle. They estimate the luminosity enhancement in the case of SLAC Linear Collider beam design parameters, and discuss limitations and possible improvements in plasma-lens performance. (7 References). |
| title: | Beam transport, acceleration and compression studies in the Fermilab high-brightness photoinjector |
| conference: | 1998 Linear Accelerator Conference |
| year: | 1998 |
| authors: | J. Carneiro,R. Carrigan,M. Champion,A. Cianchi,E. Colby,P. Colestock,H. Edwards,J. Fuerst,W. Hartung,K. Koepke,M. Kuchnir,L. Spentzouris,M. Fitch,A. Fry,A. Melissinos,B. Taylor,P. Michelato,D. Sertore,C. Pagani,J. Rosenzweig |
| abstract: | A photoinjector is being constructed in order to produce a pulse train of up to 800 electron bunches, each with 8 nC of charge and a 3.5 ps rms bunch length. The spacing between bunches within a train is 1 s and the train repetition rate is 1?10 Hz. The desired transverse emittance is <20 mm mrad. An rf photo-gun delivers a bunched 4?5 MeV beam which will be accelerated to 14?18 MeV by a 9- cell superconducting cavity and compressed magnetically. Measurements have been done on the beam delivered by a first prototype rf gun; installation of a new rf gun, the 9-cell cavity, and the bunch compressor is in progress. |
| title: | Beam-cavity interaction in electron storage rings |
| journal: | Nuclear Instruments & Methods |
| vol-pages: | 475-85 |
| year: | 1975 |
| authors: | E. Keil,C. Pellegrini,A. Turrin,M. Sessler |
| abstract: | A formal expression is obtained for the energy loss per turn, of a rigid bunch of electrons, to a closed cylindrical cavity with quality factor Q. The expression is valid provided the diameter of the entrance and exit ports for the beam are small compared to the bunch length. The effect of the ports is studied in an independent computational method. The energy loss is numerically evaluated for a range of parameters of interest to electron storage rings. (13 References). |
| title: | Beam-plasma interaction experiments at the UCLA Neptune Laboratory |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | M. Thompson,C. Clayton,J. England,J. Rosenzweig,H. Suk |
| abstract: | We are currently planning several beam-plasma interaction experiments using the high quality 16 MeV electron beam produced by the Neptune 1.625-cell photoinjector and PWT linac. The underdense (n_b > n_0) plasma lens experiment will examine the focusing of a 4 nC beam of 30 psec pulse duration as it passes through a thin 2 cm Ar plasma lens. We are also developing a negative R_56 compressor beamline that will allow us to create ramped sub-picosecond beams of a shape well suited for driving large amplitude plasma wake fields and producing high transformer ratios. Simulations made using the 2-1/2 dimensional particle-in-cell code MAGIC indicate that we could use these ramped beams to produce fields of up to 10 GeV/m in a 10(16) cm(-3) plasma. Ramped beams are also suitable for driving plasma density gradient trapping experiments. When such a beam passes through a region where the plasma density drops suddenly the fast variation of the wake fields traps several pC of plasma electrons in the accelerating portion of the wake field. |
| title: | Boiling the Vacuum with an X-ray FEL |
| conference: | APS April Meeting |
| year: | 2000 |
| authors: | C. Pellegrini |
| abstract: | We discuss the possibility of producing an electromagnetic field on the order of the Schwinger critical field by focusing the X-ray beam produced by the X-ray free-electron laser, LCLS, under development by a SLAC-ANL-BNL-LANL-UCLA collaboration. We also discuss an experiment which would use this very large field to test QED through the production of electron-positron pairs in vacuum, with no real particles being present in the initial state. |
| title: | Bunch length measurement of picosecond electron beams from a photoinjector using coherent transition radiation |
| conference: | ICFA Second Generation Plasma Acceleration Workshop |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | A. Murokh,J. Rosenzweig,M. Hogan,H. Suk,G. Travish,U. Happek |
| abstract: | The bunch length of an electron beam derived from the UCLA Saturnus photoinjector has been measured using a 45 degrees CTR foil. The sudden change of electrons boundary conditions cause them to radiate (transition radiation) with the spectral power entirely dependent upon the degree of coherency, which strongly relates to the beam size. A polarizing Michelson interferometer allowed measurement of the auto-correlation of the coherent transition radiation signal. An analysis method was developed to compensate for undetected low-frequency radiation and systematically extract the bunch length information for a specific beam model. This analysis allowed observation of pulse lengthening due to the space charge, as well as compression with the variation of the RF injection phase. The hypothesis of a satellite beam has been also tested using this analysis. (8 References). |
| title: | CAMAC Educational Material |
| format: | unpublished |
| year published: | 7/22/1991 |
| year authored: | 1991 |
| authors: | . |
| abstract: | This handout contains copies of mini-tutorials from various company catalogs. The two introductions to the CAMAC standard are worth while reading for all group members. The two GPIB reviews are useful for anyone using or planning on using GPIB instruments. Finally, a handy glossary is attached. |
| title: | CAMAC Hardware Selection for SATURNUS |
| format: | tech note |
| year: | 1991 |
| authors: | . |
| abstract: |
| title: | Calculation of Coherent Radiation from Ultra-short Electron Beams Using a Liénard-Wiechert Based Simulation Code |
| format: | |
| year: | 2004 |
| authors: | A. Flacco,M. Fairchild,S. Reiche,J.B Rosenzweig,L. Giannessi,M. Quattromini |
| abstract: | The coherent radiation emitted by electrons in high brightness beam-based experiments is important from the viewpoints of both radiation source development, and the understanding and diagnosing the basic physical processes important in beam manipulations at high intensity. While much theoretical work has been developed to aid in calculating aspects of this class of radiation, these methods do not often produce accurate information concerning the experimentally relevant aspects of the radiation. At UCLA, we are particularly interested in coherent synchrotron radiation and the related phenomena of coherent edge radiation, in the context of a fs-beam chicane compression experiment at the BNL ATF. To analyze this and related problems,we have developed aprogramthat acts as an extension to the Liénard-Wiechert-based 3D simulation code TREDI, termed FieldEye. This program allows the evaluation of electromagnetic fields in the time and frequency domain in an arbitrary 2D detector planar area.We discuss here the implementation of the FieldEye code, and give examples of results relevant to the case of the ATF chicane compressor experiment. |
| title: | Characterization of an 800 nm SASE FEL at saturation |
| conference: | 23rd International Free Electron Laser Conference |
| year published: | 2002 |
| year authored: | 2001 |
| authors: | A. Tremaine,P. Frigola,A. Murokh,C. Pellegrini,S. Reiche,J. Rosenzweig,M. Babzien,I. Ben-Zvi,E. Johnson,R. Malone,G. Rakowsky,J. Skaritka,X. Wang,K. Van Bibber,L. Bertolini,J. Hill,G. Le Sage,M. Libkind,A. Toor,R. Carr,M. Cornacchia,L. Klaisner,H. Nuhn,R. Ruland |
| abstract: | Visible to Infrared SASE Amplifier is a free electron laser (FEL) designed to saturate at a radiation wavelength of 800 nm within a 4 m long, strong focusing undulator. A large gain is achieved by driving the FEL with 72 MeV, high brightness beam of BNL's accelerator test facility. We present measurements that demonstrate saturation in addition to the frequency spectrum of the FEL radiation. Energy, gain length and spectral characteristics are compared and shown to agree with simulation and theoretical predictions. (16 References). |
| title: | Characterization of plasma accelerators with RF linac terminology |
| conference: | ICFA Second Generation Plasma Acceleration Workshop |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | A. Ogata,J. Rosenzweig,M. Ferrario |
| abstract: | The physics of plasma acceleration is described by using RF linac terminology such as shunt impedance, filling time, transit time factor, etc. It is shown that some differences between conventional RF accelerators and plasma accelerators make it difficult to import the RF linac terminology directly into the new field. For example, the shunt impedance is of limited use and the filling time is no use in wake-field accelerators with single-drive beams or single-pump pulses. The beatwave accelerator, a driven oscillator system, has in a sense more similarity to RF linacs than wake-field accelerators. It was shown that plasma wave decay due to collisions and modulational instability seriously deteriorate the quality factor. (26 References). |
| title: | Characterizing The Electron Beam For The Aps Leutl Free Electron Laser |
| conference: | 2nd ICFA Advanced Accelerator Workshop on the Physics of High Brightness Beams |
| year published: | 2000 |
| year authored: | 1999 |
| authors: | G. Travish,J. Lewellen,M. Hahne |
| abstract: | The Advanced Photon Source (APS) Low-Energy Undulator Test Line (LEUTL) project was originally intended to test and characterize advanced undulator designs via electron beambased diagnostics technique. It is presently being used to conduct free electron laser (FEL) research for a future fourth-generation light source. The APS injector linac has been upgraded to deliver a beam suitable for these FEL tests. The project has as an initial goal the operation of a self amplified spontaneous emission (SASE) device operating in the visible at 530 nm (green light). The visible FEL requires a 217 MeV moderately high brightness beam with a peak current of 100 A or greater, a normalized rms emittance of 5 ?m or less, and an energy spread of 0.1% or better. Beam characterization is fundamental to being able to match experimental results with theoretical models. This paper describes the LEUTL FEL, lists the major goals, the beam diagnostics, and presents the initial electron beam measured properties. Future plans are also discussed. |
| title: | Charge and Wavelength Scaling of RF Photoinjector Designs |
| format: | |
| year published: | September 21, 1994 |
| year authored: | 1994 |
| authors: | J. Rosenzweig,E. Colby |
| abstract: | The optimum design of an emittance compensated rf photoinector is very complicated and time-consuming, relying heavily on multi-particle simulations without good analytical models as a guide. Emittance compensated designs which have been developed, however, can be used to generate other designs with no additional effort if the original design is scaled correctly. This paper examines the scaling of rf photoinjector design with reqpect to charge and wavelength, and presents emittance and brightness scaling laws for these variables. Parametric simulation studies are presented to illustrate these scaling laws. Deviations from scaling and practical considerations are also discussed. |
| title: | Charge and Wavelength Scaling of RF Photoinjector Designs |
| conference: | 6th Advanced Accelerator Concepts Workshop |
| year published: | 1995 |
| year authored: | 1994 |
| authors: | . |
| abstract: | The optimum design of an emittance compensated rf photoinjector is very complicated and time-consuming, relying heavily on multi-particle simulations without good analytical models as a guide. Emittance compensated designs which have been developed, however, can be used to generate other designs with no additional effort if the original design is scaled correctly. This paper examines the scaling of rf photoinjector design with respect to charge and wavelength, and presents emittance and brightness scaling laws for these variables. Parametric simulation studies are presented to illustrate these scaling laws. Deviations from scaling and practical considerations are also discussed. |
| title: | Charge and Wavelength Scaling of RF Photoinjectors: A Design Tool |
| conference: | 1995 Particle Accelerator Conference |
| year: | 1995 |
| authors: | J. Rosenzweig,E. Colby |
| abstract: | The optimum design of an emittance compensated rf photoinjector is very complicated and time-consuming, relying heavily on multi-particle simulations without good analytical models as a guide. Emittance compensated designs which have been developed, however, can be used to generate other designs with no additional effort if the original design is scaled correctly. This paper examines the scaling of rf photoinjector design with respect to charge and wavelength, and presents emittance and brightness scaling laws for these variables. Parametric simulation studies are presented to illustrate these scaling laws. A practical design for the TESLA FEL rf photo-injector is developed using these scaling techiniques. |
| title: | Chicane compressor development for BNL ATF- applications to SASE FEL |
| conference: | 22nd International Free Electron Laser Conference |
| year published: | 2001 |
| year authored: | 2000 |
| authors: | R. Agustsson,J. Rosenzweig |
| abstract: | A chicane compressor is being designed and constructed at UCLA for implementation at the BNL Accelerator Test Facility. The beam optics, including collective fields, and expected performance of the device has been simulated using TRACE3D and ELEGANT. Based on these studies, as well as constraints due to downstream ATF optics, the chicane magnet specifications were determined. The dipole magnets were designed using AMPERES 3D magnetostatic modeling, and have been constructed. Implementation of this device at the ATF, as well as initial physics experiments on coherent synchrotron radiation emission (and associated emittance growth) at 70 MeV, and expected performance enhancement of the VISA SASE FEL experiment, are discussed. |
| title: | Chirped-beam two-stage SASE-FEL for high power femtosecond X-ray pulse generation |
| conference: | 23rd International Free Electron Laser Conference |
| year published: | 2002 |
| year authored: | 2001 |
| authors: | C. Schroeder,C. Pellegrini,S. Reiche,J. Arthur,P. Emma |
| abstract: | A method for generating femtosecond duration X-ray pulses using a single-pass free-electron laser (FEL) is presented. This method uses an energy-chirped electron beam propagating through an undulator to produce a frequency-chirped X-ray pulse through self-amplified spontaneous emission (SASE). After the undulator, we consider passing the radiation through a monochromator. The frequency is correlated to the longitudinal position within the pulse; therefore, by selecting a narrow bandwidth, a short temporal pulse will be transmitted. The short pulse radiation is used to seed a second undulator, where the radiation is amplified to saturation. In addition to short pulse generation, this scheme has the ability to control shot-to-shot fluctuations in the central wavelength due to electron beam energy jitter. We present calculations of the radiation characteristics produced by a chirped-beam two-stage SASE?FEL, and consider the performance of the chirped-beam two-stage option for the Linac Coherent Light Source. |
| title: | Chirped-beam two-stage SASE-FEL for high power femtosecond X-ray pulse generation |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | . |
| abstract: | We present a method for generating femtosecond duration X-ray pulses using a single-pass free-electron laser (FEL). This method uses an energy-chirped electron beam to produce a frequency-chirped X-ray pulse through self-amplified spontaneous emission (SASE). After the undulator we consider passing the radiation through a monochromator. The frequency is correlated to the longitudinal position within the pulse, and therefore, by selecting a narrow bandwidth, a short temporal pulse will be transmitted. The short pulse radiation is used to seed a second undulator, where the radiation is amplified to saturation. In addition to short pulse generation, this scheme has the ability to control shot-to-shot fluctuations in the central wavelength due to electron beam energy jitter. We present calculations of the radiation characteristics produced by a chirped-beam two-stage SASE-FEL, and consider the performance of the chirped-beam two-stage option for the for the Linac Coherent Light Source (LCLS). |
| title: | Chirped-beam two-stage SASE-FEL for high power femtosecond x-ray pulse generation |
| conference: | Conference on Optics for Fourth-Generation X-Ray Sources |
| year: | 2001 |
| authors: | C. Schroeder,C. Pellegrini,S. Reiche,J. Arthur,P. Emma |
| abstract: | We present a method for generating femtosecond duration x-ray pulses using a single-pass free-electron laser (FEL). This method uses an energy-chirped electron beam to produce a frequency-chirped x-ray pulse through self-amplified spontaneous emission (SASE). After the undulator we consider passing the radiation through a monochromator. The frequency is correlated to the longitudinal position within the pulse, and therefore, by selecting a narrow bandwidth, a short temporal pulse will be transmitted. The short pulse radiation is used to seed a second undulator, where the radiation is amplified to saturation. In addition to short pulse generation, this scheme has the ability to control shot-to-shot fluctuations in the central wavelength due to electron beam energy jitter. We present calculations of the radiation characteristics produced by a chirped-beam two-stage SASE-FEL, and consider the performance of the chirped-beam two-stage option for the Linac Coherent Light Source (LCLS). |
| title: | Chirped-beam two-stage free-electron laser for high-power femtosecond x-ray pulse generation |
| journal: | Journal of the Optical Society of America B-Optical Physics |
| vol-pages: | 1782-89 |
| year: | 2002 |
| authors: | C. Schroeder,C. Pellegrini,S. Reiche,J. Arthur,P. Emma |
| abstract: | A method for generating femtosecond-duration x-ray pulses with a free-electron laser is presented. This method uses an energy-chirped electron beam propagating through an undulator to produce a frequency-chirped x-ray pulse by self-amplified spontaneous emission. A short temporal pulse is created by use of a monochromator to select a narrow radiation bandwidth. A second undulator is used to amplify the short-duration radiation. The radiation characteristics produced by a chirped-beam two-stage free-electron laser are calculated, and the performance of the chirped-beam two-stage option for the Linac Coherent Light Source is considered. |
| title: | Coherent Radiation Diagnosis of Self Amplified Spontaneous Emission free Electron Laser-Derived Electron beam Microbunching |
| format: | thesis |
| year: | 1999 |
| authors: | A. Tremaine |
| abstract: | This thesis presents an experiment in which the longitudinal profile of an electron beam was measured by studying the coherrent transition radiation (CTR) emitted when the beam strikes a thin conducting foil. A high gain Self Amplified Spontaneous Emission (SASE) Free Electron laser (FEL) was implemented and the source fo the longitudinal beam profile modulation. Diagnostics measuring very short periodic electron beam modulation will be necessary for future experiments in which the modulating wavelength will be several microns. Up to this point, there have been reliable tools used for such longitudinal beam profile measurements. However, the limits of resolution in these devices are being approached and new and less expensive methods are needed. Transition radiation from an electron beam striking a metallic surface is an easily emplementable and inexpensive diagnostic and is shown to be a reliable diagnostic for the future. This thesis presents the theoretical calculation of the expected CTR photon spectrums and compares the analysis with an experiment recently done on an electron beam which has been longitudinally modulated by SASE FEL. The accelerator beamline and its parameters important to the experiment are described. Also, discussed, are the requirements on the system needed for the best CTR emission possible and the importance in choosing a good metallic radiating foil. Results from the data are compared with computer simulation in which these issues are taken into account. Also, the experimental results point out approximations used in traditional transition radiation modeling that will not be valid in future CTR experiemnts and more rigorous theorectical analysis will be needed. |
| title: | Coherent Transition Radiation Dignosis of Microbunching at the Exit of a Free-Electron Laser Undulator |
| format: | |
| year published: | March 6, 1995 |
| year authored: | 1995 |
| authors: | J. Rosenzweig,G. Travish,A. Tremaine |
| abstract: | The action of the free-electron laser instability (FEL) on an electron beam produces a longitudinal density modulation with a periodicity near the resonant radiation wavelength. This modulation, which can produce femtosecond or shorter microbunches inside of a macroscopic picosecond electron pulse, has been proposed for use as a prebunching injector for both higher harmonic FELs and short wavelength accelerators. Standard methods involving streak cameras or beam sweeping with dipole mode cavities will certainly fail to provide information about this longitudinal microstructure, however. In this paper we explore the use of coherent transition radiation generated from a foil a the exit of an FEL undulator to diagnose both the lognitudinal and transverse electron microbunch structure. |
| title: | Coherent X-rays from PEP |
| conference: | 1991 Particle Accelerator Conference |
| year: | 1991 |
| authors: | S. Baird,H. Nuhn,R. Tatchyn,H. Winick,A. Fisher,J. Gallardo,C. Pellegrini |
| abstract: | The authors explore the use of a large-circumference, high-energy electron-positron collider such as PEP to drive a free-electron laser (FEL), producing high levels of coherent power at short wavelengths. They consider self-amplified spontaneous emission (SASE), in which electron bunches with low emittance, high peak current, and small energy spread radiate coherently in a single pass through a long undulator. The authors also explore various combinations of electron-beam and undulator parameters, as well as special undulator designs and optical klystrons (OKs), to reach high average or peak coherent power at wavelength around 40 AA by achieving significant exponential gain or full saturation. Examples are presented for devices that achieve high peak coherent power (up to about 400 MW) with lower average coherent power (about 20 mW) and other devices which produce a few watts of average coherent power. (22 References). |
| title: | Coherent and Collective States in Beam-Radiation Interaction |
| format: | |
| year: | 1998 |
| authors: | C. Pellegrini |
| abstract: | We review the theory of the free-electron laser collective instability, and the properties of the electron beam and the radiation feild state produced by the instability. We also present some recent experimental results supporting the theory. |
| title: | Coherent transition radiation diagnosis of electron beam microbunching |
| journal: | Nuclear Instruments & Methods A |
| vol-pages: | 255-9 |
| year: | 1995 |
| authors: | J. Rosenzweig,G. Travish,A. Tremaine |
| abstract: | The action of the free-electron laser instability (FEL) on an electron beam produces a longitudinal density modulation with a periodicity near the resonant radiation wavelength. This modulation, which can produce femtosecond or shorter microbunches inside of a macroscopic picosecond electron pulse, has been proposed for use as a prebunching injector for both higher harmonic FELs and short wavelength accelerators. Standard methods involving streak cameras or beam sweeping with dipole mode cavities will certainly fail to provide information about this longitudinal microstructure, however. In this paper we explore the use of coherent transition radiation generated from a foil at the exit of an FEL undulator to diagnose both the longitudinal and transverse electron microbunch structure. (12 References). |
| title: | Coherent transition radiation-based diagnosis of electron beam pulse shape |
| conference: | 8th Advanced Accelerator Concepts Workshop |
| year published: | 1999 |
| year authored: | 1998 |
| authors: | J. Rosenzweig,A. Murokh,A. Tremaine |
| abstract: | The bunch shapes of an electron beams is increasingly difficult to measure, as the time-scales of interest are now sub-picosecond. We discuss here the use of coherent transition radiation (CTR) for such measurements. Two types of measurements are presented: the deduction of macroscopic (0.3 psec resolution) pulse profile using interferometry, and the examination of microbunch (50 fsec) structure from an FEL-bunched beam using spectral characteristics of the CTR. For the macrobunch measurement we discuss the problem of missing low frequency radiation and one solution for extracting meaningful data with this problem are presented. For microbunch CTR, we examining initial spectrally-resolved measurements, and some interesting deviations in the CTR spectrum from the standard theoretical predictions. (23 References). |
| title: | Cold Test Measurements of the UCLA Photo-Injector |
| format: | unpublished |
| year published: | April 30, 1993 |
| year authored: | 1993 |
| authors: | S. Hartman,M. Hogan |
| abstract: |
| title: | Collective Instability of a Free-Electron Laser Including Space-Charge and Harmonics |
| journal: | Optics Communications |
| vol-pages: | 197-202 |
| year: | 1985 |
| authors: | J. Murphy,C. Pellegrini,R. Bonifacio |
| abstract: | The effects of harmonics, space charge and electron energy spread on the collective instability regime of an electron beam coupled to a planar undulator are analyzed. Both analytical and numerical results are presented. |
| title: | Collective instabilities and high-gain regime free electron laser |
| conference: | Topical Meeting on Free Electron Generation of Extreme Ultraviolet Coherent Radiation |
| year published: | 1984 |
| year authored: | 1983 |
| authors: | R. Bonifacio,C. Pellegrini,L. Narducci |
| abstract: | Studies the conditions for collective instability of the electron beam-undulator-radiation field of free electron lasers. The authors derive the characteristic complex frequencies of the FEL. From this result, the small-signal gain formula is obtained. They consider the problem of the initiation of laser action and growth of the radiation field from noise. The nonlinear regime is studied numerically. (14 References). |
| title: | Collective instabilities and high-gain regime in a free electron laser |
| journal: | Optics Communications |
| vol-pages: | 373-8 |
| year: | 1984 |
| authors: | R. Bonifacio,C. Pellegrini,L. Narducci |
| abstract: | The authors study the behavior of a free electron laser in the high gain regime, and the conditions for the emergence of a collective instability in the electron beam-undulator-field system. The authors' equations, in the appropriate limit, yield the traditional small gain formula. In the nonlinear regime, numerical solutions of the coupled equations of motion support the correctness of their proposed empirical estimator for the build-up time of the pulses, and indicate the existence of optimum parameters for the production of high peak-power radiation. (11 References). |
| title: | Collective instabilities in accelerator and storage rings |
| conference: | Andrew Sessler Symposium on the Physics of Beams |
| year published: | 1996 |
| year authored: | 1993 |
| authors: | C. Pellegrini |
| abstract: | We describe the initial discovery of collective beam instability in accelerator and storage rings, the work that was done in the 60's to obtain a theory of these effects, and their impact on the developments of electron-positron and proton-proton colliders. (13 References). |
| title: | Colliding-beam accelerators |
| format: | |
| year: | 1972 |
| authors: | C. Pellegrini |
| abstract: | Three electron-positron storage rings for colliding beams at Frascati, Novosibirsk, and Orsay, and one proton-proton storage ring at CERN, are now operating, and a large number of high energy physics experiments are being performed on them. The successful operation of these storage rings has given to physicists the possibility of using colliding beams to reach very high center of mass energies applicable to the study of elementary particle reactions. The intersecting storage ring (ISR) at CERN and Adone at Frascati presently provide the maximum center of mass energies (56 and 3 GeV respectively) for proton-proton and electron-positron interactions. The author discusses single particle motion in storage rings, limits on stored current and current density, beam lifetime, luminosity and its limitations, and coherent instabilities. (76 References). |
| title: | Commissioning and measurements of the Neptune photo-injector |
| conference: | 9th Advanced Accelerator Concepts Workshop |
| year published: | 2001 |
| year authored: | 2000 |
| authors: | S. Anderson,M. Loh,P. Musumeci,J. Rosenzweig,H. Suk,M. Thompson |
| abstract: | The photo-injector for the Neptune Advanced Accelerator Laboratory is introduced. Its component parts, including the radio frequency gun, photo-cathode drive laser system, booster linac, RF system, chicane compressor, beam diagnostics, and control system are described. The injector is designed to produce high brightness, short pulse electron beams. Measurements of the photo-injector beams including quantum efficiency, emittance, pulse length, and pulse compression are presented. (21 References). |
| title: | Commissioning of the Neptune Photoinjector |
| conference: | APS April Meeting |
| year: | 2000 |
| authors: | S. Anderson,J. Rosenzweig,A. Burke,X. Ding,M. Loh,P. Musumeci,C. Pellegrini,H. Suk,M. Thompson,C. Clayton,C. Joshi,K. Marsh,P. Muggli |
| abstract: | The status of the commissioning of the rf photoinjector in the Neptune advanced accelerator laboratory is discussed. The component parts of the photoinjector, the rf gun, photocathode drive laser system, booster linac, rf system, chicane compressor, beam diagnostics systems, and control system are described. Recent improvements in the rf gun, rf timing, and chicane compressor systems are detailed. This injector is designed to produce short pulse length, high brightness electron beams. Experiments planned for the immediate future are described. Initial measurements of various beam parameters are presented. |
| title: | Commissioning of the Neptune photoinjector |
| conference: | 1999 Particle Accelerator Conference |
| year: | 1999 |
| authors: | S. Anderson,J. Rosenzweig,K. Bishofberger,X. Ding,T. Holden,A. Murokh,C. Pellegrini,H. Suk,A. Tremaine,C. Clayton,C. Joshi,K. Marsh,P. Muggli,R. Agustsson,S. Anderson,P. Musumeci,M. Loh,M. Thompson,S. Boucher,A. Burke,J. England |
| abstract: | The status of the commissioning of the RF photoinjector in the Neptune advanced accelerator laboratory is discussed. The component parts of the photoinjector, the RF gun, photocathode drive laser system, booster linac, RF system, chicane compressor, beam diagnostics systems, and control system are described. This injector is designed to produce short pulse length, high brightness electron beams. Experiments planned for the immediate future are described. Initial measurements of various beam parameters are presented. (10 References). |
| title: | Commissioning of the Neptune photoinjector |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | R. Agustsson,J. Rosenzweig,S. Anderson,P. Musumeci,M. Loh,M. Thompson,S. Boucher,A. Burke,J. England |
| abstract: | The status of the RF photoinjector in the Neptune advanced accelerator laboratory is discussed. The components of the photoinjector: the RF gun and booster linac, chicane compressor, and beam diagnostic systems are described. Measurement techniques used to diagnose the short pulse length, high brightness beam are detailed and measurements of emittance and pulse compression are given. The effect of the pulse compressor on transverse emittance is explored. (11 References). |
| title: | Commissioning of the UCLA PEGASUS Photoinjector Laboratory |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | S. Telfer,S. Reiche,J. Rosenzweig,P. Frigola,G. Andonian |
| abstract: | The PEGASUS Photoinjector has been commissioned at UCLA. The Plane Wave Transformer Photoinjector provides a high-brightness 17 MeV beam that will be used for numerous beam-radiation studies. Some of these will include SASE FEL, transition radiation from non-standard surfaces, and monochromatic x-ray production via PXR and Thompson scattering. |
| title: | Comparison of the FEL and CSR Instabilities |
| format: | unpublished |
| year published: | April 19, 2002 |
| year authored: | 2002 |
| authors: | S. Reiche |
| abstract: | FEL and CSR instabilities have same principle of interaction between electron beam and synchrotron radiation, but the signature is different for the different longitudinal scales. Beside the FEL these instabilities are regarded as degrading affects on the beam properties, imposing limitation on the operation range of the accelerator. |
| title: | Comparison of the coherent radiation-induced microbunching instability in a free-electron laser and a magnetic chicane |
| journal: | Physical Review Special Topics-Accelerators & Beams |
| vol-pages: | 040702 |
| year: | 2003 |
| authors: | S. Reiche,J. Rosenzweig |
| abstract: | A self-amplified spontaneous emission free-electron laser (SASE FEL) is a device which is based on the creation of a very intense, relativistic electron beam which has very little temperature in all three phase planes. The beam in this system is described as having "high brightness,'' and when it is bent repetitively in a magnetic undulator, undergoes a radiation-mediated microbunching instability. This instability can amplify the original radiation amplitude at a particular, resonant wavelength by many orders of magnitude. In order to obtain high brightness beams, it is necessary to compress them to obtain higher currents than available from the electron source. Compression is accomplished by the use of magnetic chicanes, which are quite similar to, if much longer than, a single period of the undulator. It should not be surprising that such chicanes also support a radiation-mediated microbunching interaction, which has recently been investigated, and has been termed coherent synchrotron radiation (CSR) instability. The purpose of this paper is to compare and contrast the characteristics of the closely related FEL and CSR microbunching instabilities. We show that a high-gain regime of the CSR instability exists which is formally similar to the FEL instability. |
| title: | Compensation of FEL gain reduction by emittance effects in a strong focusing lattice |
| conference: | 21st International Free Electron Laser Conference |
| year published: | 2000 |
| year authored: | 1999 |
| authors: | S. Reiche |
| abstract: | As the constraint of a small transverse emittance becomes more severe, the higher the electron beam energy in an FEL. To compensate for the transverse and thus the longitudinal velocity spread. a compensation scheme has been proposed previously by Derbenev and Sessler et al., for Free Electron Lasers by introducing a correlation between the energy and the average betatron amplitude of each electron. This compensation scheme is based on a constant absolute value of the transverse velocity, a feature of the natural focusing of undulators. and does not include strong focusing of a superimposed quadrupole lattice. This paper focuses on the electron motion in a strong focusing lattice with a variation in the axial velocity. The resulting reduction of the compensation efficiency is analyzed using simulations. It is seen that the compensation scheme is not much affected if the lattice cell length is shorter than the gain length. For the results presented in this paper, the parameters of the proposed TESLA X-ray FEL have been used. |
| title: | Conceptual Design of a High Luminosity 510 MeV Collider |
| conference: | 1991 Particle Accelerator Conference |
| year: | 1991 |
| authors: | C. Pellegrini,M. Cornacchia,D. Robin |
| abstract: | We discuss the magnetic lattice design of a high luminosity 510 MeV electron-positron collider, based on high field superconduction bending dipoles. The design criteria are flexibility in the choice of the tune and beta functions at the interaction point, horizontal emittance larger than 1 mm mrad to produce a luminosity larger than 10(32) cm(-2)s(-1), large synchrotron radiation damping rate, and large momentum compaction. The RF system parameter are chosen to provide a short bunch length also when the beam energy spread is determined by the microwave instability. A satisfactory ring dynamic aperture, and a simultaneous small value of the horizontal and vertical beta function at the interaction point, we expect will be achieved by using Cornacchia Halbach modified sextupoles. |
| title: | Conceptual design of a 300 GeV accelerator based on the Inverse Free Electron Laser mechanism |
| conference: | 12th International Conference on High-Energy Accelerators |
| year: | 1983 |
| authors: | C. Pellegrini,P. Sprangle,W. Zakowicz |
| abstract: | The authors describe an Inverse Free Electron Laser Accelerator and how it can be used to accelerate electrons to energies of several hundred GeV, with an average acceleration rate of 150 MeV/m. They discuss the system scaling laws for several undulator designs and the methods for laser beam transport over the required distance of a few kilometers. (9 References). |
| title: | Considerations for Conical Horn Antenna Design optimizing Cerenkov radiation from hollow cylindrical dielectric tube |
| format: | tech note |
| year: | 2004 |
| authors: | Hristo Badakov |
| abstract: |
| title: | Creation of plasma density transitions short compared to the plasma skin depth |
| format: | preprint |
| year: | 2004 |
| authors: | M. Thompson,J. Rosenzweig,G. Travish |
| abstract: | A plasma based electron beam source apparatus is described which creates a plasma with two distinct density regions separated by a transition which is shorter than the plasma skin depth $k^{-1}_{p}$ of either region. This sharp density modulation is achieved by using a perforated stainless steel screen to filter half of a diffusing plasma column. A simple physical model predicts that the length of the plasma density transition will vary with the distance from the screen. For a weakly magnetized plasma, the transition length will be twice the distance, on a line normal to the screen plane, from the screen edge to the location where the transition is measured. The plasma column is generated using an argon discharge plasma source. It has a peak density of approximately 3.5 x 10$^{13}$ cm$^{-3}$ and a FWHM width of 5 cm. The discharge source utilizes a 7.5 cm diameter LaB$_{6}$ disc cathode heated to $1300^{\circ}$ C using a graphite heater. The plasma column is filtered with a 78 $\mu$m thick stainless steel sheet with 152 $\mu$m holes and 21\% open area. Plasma density transitions with lengths between 0.74$k^{-1}_{p}$ and 0.95$k^{-1}_{p}$ were measured. |
| title: | Creation of plasma density transitions short compared to the plasma skin-depth |
| journal: | REVIEW OF SCIENTIFIC INSTRUMENTS |
| vol-pages: | 76:013303 |
| year: | 2005 |
| authors: | M. Thompson,J. Rosenzweig,G. Travish |
| abstract: | A plasma based electron beam source apparatus is described which creates a plasma with two distinct density regions separated by a transition which is shorter than the plasma skin depth kp^−1 of either region. This sharp density modulation is achieved by using a perforated stainless steel screen to filter half of a diffusing plasma column. A simple physical model predicts that the length of the plasma density transition will vary with the distance from the screen. For a weakly magnetized plasma, the transition length will be twice the distance, on a line normal to the screen plane, from the screen edge to the location where the transition is measured. The plasma column is generated using an argon discharge plasma source. It has a peak density of approximately 3.53 X 10^13 cm^−3 and a full width half maximum width of 5 cm. The discharge source utilizes a 7.5 cm diameter LaB6 disk cathode heated to 1300 °C using a graphite heater. The plasma column is filtered with a 78 mm thick stainless steel sheet with 152 mm holes and 21% open area. Plasma density transitions with lengths between 0.74 and 0.95 kp^−1 were measured. |
| title: | Creation, Manipulation, and Diagnosis of Intense, Relativistic Picosecond Photo-electron Beams |
| format: | thesis |
| year: | 2002 |
| authors: | S. Anderson |
| abstract: | The radio frequency photoinjector is the pre-eminent source for advanced electron beam applications that require extremely high phase space density (high brightness) beams. Because of their high phase space density, the collective fields generated by photoinjector beams dominate their behavior. These space-charge fields influence every aspect of the beam's handling, including its acceleration, measurement, and transport. The effects of spece-charge must be carefully considered in all of these beam handling procedures in order to deliver the highest brightness beams possible. This dissertation investigates the space-charge dominated physical processes involved in the acceleration and propagation, emittance measurement, and magnetic compression fo photoinjector beams. In the analysis of the behavior of these beams, emphasis is placed on the techniques used to compensate for space-charge forces, and maximize beam brightness. The rectilinear motion of a space-charge cominated beam is analyzed, including both linear and nonlinear self forces, in order to determine the evolution of the beam's transverse emittance as it is accelerated and transported through the photoinjector. It is found that the emittance can be made to oscillate by judicious use of external forces, and that this oscillation can be manipulated to minimize the beam's emittance, compensating for the effects of both linear and nonlinear space-charge forces, at a given location of interest. The creation of a high brightness beam in the presence of emittance oscillations is critically dependent on phase space diagnosis. Thus the measurement of emittance of intense beams is investigated experimentally, theoretically, and in simulation, for quadrupole scanning and multi-slit based measurement techniques. The quadrupole scanning method is found to have systematic errors for space-charge dominated beams, and experimental measurements using this technique give consistently higher emittance values than both the slit-based measurements and simulations. Finally, the measurement of emittance growth and transverse phase space distortions induced by magnetic compression of the beam to sub-picosecond lengths is described. A clear bifurcation of the phase space is observed when the beam is strongly compressed. This effect is found to be correlated to the folding of the beam distribution in configuration space. |
| title: | Crossing of an incoherent integral resonance in the electron ring accelerator |
| journal: | Nuclear Instruments & Methods |
| vol-pages: | 109-16 |
| year: | 1970 |
| authors: | C. Pellegrini,A. Sessler |
| abstract: | In one mode of operation of an electron ring accelerator (ERA), at the end of compression rings are slowly moved through the radial integral betatron resonance Q_r=1. Although the coherent radial oscillation frequency of the ring as a whole remains below unity, the oscillation frequencies of individual electron are (incoherently) caused to pass through the resonance because of the additional focusing from ions trapped in the ring. In this paper the effect of field errors on ring major and minor radii is evaluated-theoretically-for the cases in which the spread in the square of the electron oscillation frequency ( Delta(2)) is (a) much smaller and (b) much larger than the contribution to the square of the oscillation frequency from the ions ( Lambda(2)). |
| title: | DOE Review |
| format: | unpublished |
| year published: | February 17, 1993 |
| year authored: | 1993 |
| authors: | . |
| abstract: |
| title: | Degradation of Longitudinal Phase Space Distribution of the LCLS Beam by Compton Back-Scattering |
| format: | unpublished |
| year published: | January 24, 1993 |
| year authored: | 1993 |
| authors: | J. Rosenzweig |
| abstract: | The requirements on the phase and amplitude jitter of the photoinjector laser in teh LCLS are very stringent. These can be eased if the incoherent energy spread in the beam is increased, decreasing the sensitivity of the bunch compression process. There are few good ways of increasing the incoherent, as opposed to the coherent, energy spread, which can be easily increased by rephasing the rf, or by space charge. A radiative or a collisional process must be used to increase the incoherent energy spread, in order to make the energy change independent of phase. Here we examine the feasibility of using the back-scattering of photons from an intense, one picosecond laser beam. We assume that we can use a laser beam (1047 nm wavelength, Nd:YLF), chosen to allow it to drive both the cathode (after quadrupling), and the longitudinal phase space degrader. |
| title: | Demonstration of Electron-Beam Self-Focusing in Plasma Wake Fields |
| journal: | Physics of Fluids B-Plasma Physics |
| vol-pages: | 1376-83 |
| year: | 1990 |
| authors: | J. Rosenzweig,P. Schoessow,B. Cole,C. Ho,W. Gai,R. Konecny,S. Mtingwa,J. Norem,M. Rosing,J. Simpson |
| abstract: |
| title: | Demonstration of electron beam self-focusing in plasma wake fields |
| conference: | Annual Meeting of the Division of Plasma Physics of the APS |
| year published: | 1990 |
| year authored: | 1989 |
| authors: | J. Rosenzweig,P. Schoessow,B. Cole,C. Ho,W. Gai,R. Konecny,S. Mtingwa,J. Norem,M. Rosing,J. Simpson |
| abstract: | The direct observation of wake-field self-focusing of an electron beam in plasma is reported. The dynamics of beam self-pinching and the fast collisionless evolution of a Bennett-like, near-equilibrium profile are examined theoretically and computationally. The experimental results are compared to predictions of the analysis and discussed in the context of application to the plasma lens and the plasma wake-field accelerator. (19 References). |
| title: | Design Considerations for a High-Efficiency High-Gain Free-Electron Laser for Power Beaming |
| conference: | 25th International Free Electron Laser Conference |
| year: | 2003 |
| authors: | C. Muller,G. Travish |
| abstract: | Power beaming from ground-based systems to space-based platforms has been proposed by a number of researchers as a means of delivering energy to orbiting satellites and stations. This paper considers the use of a seeded high-gain high-efficiency Free-Electron Laser (FEL) amplifier based on a conventional linac as the source for power beaming. While the wall-plug efficiency of a single pass FEL is likely to be considerably lower than a recirculating system, electrical efficiency is unlikely to be a serious consideration for first-generation power-beaming systems. Moreover, the simplicity of the proposed scheme scales well from existing and completed experiments. |
| title: | Design Considerations for the UCLA PBPL Slit-based Phase Space Measurement Systems |
| format: | |
| year published: | March 2, 1994 |
| year authored: | 1994 |
| authors: | J. Rosenzweig,G. Travish |
| abstract: | The phase space measurement system initially implemented by Spencer Hartmann on the UCLA PBPL rf photocathode gun has been upgraded, and a new system has been designed to measure the emittance at higher energy, after the emittance compensating drift and acceleration in the PWT linac. The purpose of this note is to describe the design criteria and physical principles involved in obtaining systems which provide the resolution in phase space measuremtns that we require. The final lit and detectro hardware designs are included; the video data acquisition and analysis will remain nearly unchanged from Hartmann's system. |
| title: | Design and Construction of High Brightness RF Photoinjectors for TESLA |
| conference: | 1995 Particle Accelerator Conference |
| year: | 1995 |
| authors: | E. Colby,V. Bharadwaj,J. Ostiguy,T. Nicol,M. Conde,J. Rosenzweig |
| abstract: | The design, construction and testing of a high brightness high bunch charge RF photoinjectormatching the requirements of the TESLA Test Facility is discussed. Engineering design work, the results of cold test measurements, and the planned experimental program are presented. Conceptual design work leading to an advanced high-brightness asymmetric emittance RF photoinjector for application to TESLA500 is also briefly discussed. |
| title: | Design and Operation of Pegasus Thermionic Cathode |
| conference: | 2003 Particle Accelerator Conference |
| year: | 2003 |
| authors: | P. Frigola,G. Andonian,S. Reiche,J. Rosenzweig,S. Telfer,G. Travish |
| abstract: | A new thermionic cathode has been developed and installed for use on The PEGASUS plane wave transformer injector. The novel design of the LaB6 cathode allows for thermionic emission as well as photoinjector operation. Test stand measurements as well as in situ operational experience are reported. |
| title: | Design and Status of the VISA II Experiment |
| conference: | 2003 Particle Accelerator Conference |
| year: | 2003 |
| authors: | G. Andonian,R. Agustsson,A. Murokh,C. Pellegrini,S. Reiche,J. Rosenzweig,G. Travish,M. Babzien,I. Ben-Zvi,V. Yakimenko,L. Palumbo,C. Vicario |
| abstract: | VISA II is the follow-up project to the successful Visible to Infrared SASE Amplifier (VISA) experiment at the Accelerator Test Facility (ATF) in Brookhaven National Lab (BNL). This paper will report the motivation for and status of the two main experiments associated with the VISA II program. One goal of VISA II is to perform an experimental study of the physics of a chirped beam SASE FEL at the upgraded facilities of the ATF. This requires a linearization of the transport line to preserve energy chirping of the electron beam at injection. The other planned project is a strong bunch compression experiment, where the electron bunch is compressed in the chicane, and the dispersive beamline transport, allowing studies of deep saturation. |
| title: | Design and operation of a novel, compact 20 MeV linac at UCLA |
| conference: | Intense Microwave and Particle Beams III |
| year: | 1992 |
| authors: | P. Davis,G. Hairapetian,C. Joshi,N. Luhmann,S. Hartman,S. Park,C. Pellegrini,J. Rosenzweig,J. Smolin |
| abstract: | A novel, compact S-band linac has been designed and is currently under construction at UCLA. It is expected to deliver high brightness, 200 A, 20 MeV electron pulses, less than 4 ps in duration from a device that is about 1 meter long. It comprises: (a) a laser photocathode driven gun that produces 4.5 MeV electron bunches from a 1/sup 1///sub 2/ cell cavity operating in the pi -mode and (b) an accelerating structure known as a plane wave transformer (PWT) designed by Swenson (1988). The design considerations of the machine and initial operating experience of the gun are discussed. The linac will be used for free electron laser, advanced accelerator research and beam-plasma experiments. (8 References). |
| title: | Design concepts of a storage ring for a high power XUV free electron laser |
| conference: | 7th International Free Electron Laser Conference |
| year published: | 1986 |
| year authored: | 1985 |
| authors: | M. Cornacchia,J. Bisognano,S. Chattopadhyay,A. Garren,K. Halbach,A. Jackson,K. Kim,H. Lancaster,J. Peterson,M. Zisman,C. Pellegrini,G. Vignola |
| abstract: | The authors report on the study of a storage ring capable of sustaining an electron beam of the quality required for a high-gain free electron laser in the vacuum ultraviolet and X-ray region. They describe a method for the optimization of the design of the storage ring where several competing and often conflicting requirements come into play. They present an example design of a ring that satisfies the required conditions of beam quality and is able to produce coherent radiation at 400 AA with tens of megawatts of peak power. (11 References). |
| title: | Design considerations for a 60 meter pure permanent magnet undulator for the SLAC Linac Coherent Light Source (LCLS) |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | R. Tatchyn,R. Boyce,K. Halbach,H. Nuhn,J. Seeman,H. Winick,C. Pellegrini |
| abstract: | In this paper we describe design, fabrication, and measurement aspects of a pure permanent magnet (PM) insertion device designed to operate as an FEL at a 1st harmonic energy of 300 eV and an electron energy of 7 GeV in the self-amplified spontaneous emission regime. (13 References). |
| title: | Design considerations for a SASE X-ray FEL |
| conference: | 22nd International Free Electron Laser Conference |
| year published: | 2001 |
| year authored: | 2000 |
| authors: | C. Pellegrini |
| abstract: | The well developed theory of short wavelength SASE-FELs is now being used to design two X-ray lasers, LCLS and Tesla-FEL. However, the physics and technology of these projects present some unique challenges, related to the very high peak current of the electron beam, the very long undulator needed to reach saturation, and the importance of preserving the beam phase-space density even in the presence of large wake-field effects. In the first part of the paper, we review the basic elements of the theory, the scaling laws for an X-ray SASE-FEL, and the status of the experimental verification of the theory. We then discuss some of the most important issues for the design of these systems, including wake-field effects in the undulator, and the choice of undulator type and beam parameters. (74 References). |
| title: | Design of High Brightness Symmetric and Asymmetric Emittance RF Photoinjectors for TESLA |
| conference: | 6th Advanced Accelerator Concepts Workshop |
| year published: | 1995 |
| year authored: | 1994 |
| authors: | E. Colby,J. Ostiguy,J. Rosenzweig |
| abstract: | Development work leading to emittance-compensated symmetric emittance and asymmetric emittance RF photoinjectors is discussed. A mature design for a symmetric emittance photoinjector is described, and current work leading to an asymmetric design is detailed. An experimental program to characterize both injectors and to explore the physical mechanism of emittance compensation using the facilities of the Argonne Wakefield Accelerator is outlined. (15 References). |
| title: | Design of a High Brightness RF Photoinjector for the SLAC Linac Coherent Light Source |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | J. Rosenzweig,L. Serafini |
| abstract: | The electron injector for the SLAC Linear Coherent Light Source[l] (LCLS) must produce a low jitter, high brightness beam. This beam must be accelerated and longitudinally compressed to yield a sub-picosecond beam which radiates a burst of self-amplified spontaneous emission xrays upon passing through a long undulator. As the gain of this amplifier is very sensitive to the emittance, energy spread and peak current the electron source and subsequent transport, acceleration, and compression systems must reproducibly give a very high quality beam. The conceptual design of an rf photocathode gun which satisfies the requirements of the LCLS is presented here. While the design peak current emitted by this gun is above 200 A, the requirements of gain length in the undulator are such that the beam must undergo longitudinal compression to raise the peak current by an order of magnitude. This compression is very much dependent on both the phase of the accelerating rf wave and the longitudinal wake-fields in the linac, and so the final bunch length will not be reproducible if the time of beam emission (laser beam injection) and/or the charge per bunch have large variations. Because of concerns on reliability and feasibility of the photoinjector, a design which takes maximum advantage of proven technology, and recent experience in photoinjector development has been explored, and is outlined below. |
| title: | Design of a high duty cycle, asymmetric emittance RF photocathode injector for linear collider applications |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | J. Rosenzweig,E. Colby,C. Jackson,T. Nicol |
| abstract: | One of the attractive features of the superconducting approach to linear collider design is that the transverse emittances demanded are much larger than in normal conducting schemes. For TESLA design parameters, the damping rings appear to be relatively large and expensive, and it is therefore of some interest to look into alternative sources. For electrons, a promising source candidate is an RF photocathode. In this paper, we present conceptual design work towards development of an asymmetric emittance RF photocathode source which can operate at the TESLA repetition rates and duty cycle, and is capable of emitting beams with the required emittances and charge per pulse. (7 References). |
| title: | Design of the Vacuum System for the High Energy Ring of an Asymmetric B-Factory Based on PEP |
| format: | unpublished |
| year: | 1991 |
| authors: | W. Barletta,M. Calderon,R. Wong,T. Jenkins |
| abstract: | The multi-ampere currents required for high luminosity operation of an asymmetric B factory leads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the dtector. We present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9GeV electron storage ring of the proposed B factory based on PEP. The excellent thermal and photo-desorption properties of Cu allows handling the high photon flux in a conventional, single chamber design with distributed ion pumps. The x-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radtiation generated by the beam. The design allows chamber commissioning in <500 hr of operation. |
| title: | Design, Construction and Testing of a Radiofrequency Electron Photoinjector for the Next Generation Linear Collider |
| format: | thesis |
| year: | 1997 |
| authors: | E. Colby |
| abstract: | The design of a high bunch charge (8 nC), low emittance (< 20 nn-mr) radiofrequency electron photoinjector matched to the requirements of the TESLA Test Facility is presented. A 1.625-cell iris-coupled pi-mode structure with high average accelerating gradient is chosen for its high shunt, impedance, simplicity, and ability to accomodate an externally mounted solenoid for simultaneous beam divergence control and emittance compensation. A novel split-solenoid focussing assembly is employed, allowing emittance compensated beam extraction over a wide range of gun gradients. Beam optics are optimized for an overall injector consisting of the electron gun followed by one linac capture section (providing acceleration to 18 MeV), and a dipole chicane for magnetic bunch compression to achieve a bunch length sigma_z of 1 mm. Analytic and simulation work yielding a space charge emittance compensated gun design in a new high charge regime is detailed. Experimental measurements made on a prototype gun and injector at the Argonne Wakefield Acclerator Facility are detailed. Experimental results indicate a beam of 8 nC charge with bunch length ~ 1.1 mm has been produced at emittances of less than 60 x 60 pi mm-mr at an energy of 16 MeV with an energy spread of 240 keV. Experimental results, although in significant disagreement (by a factor of two) with initial simulations (which assume idealized laser properties), are in fair agreement with simulations carried out using the measured performance of the laser. |
| title: | Design, Construction, Simulation and Implementation of a Magnetic Electron Bunch Compressor |
| format: | thesis |
| year: | 2004 |
| authors: | Ronald Agustsson |
| abstract: | Throughout the last half century, electron beam brightness has been the quantitative benchmark for measuring the advancement of light sources. The generation of these high brightness beams often require compaction techniques to decrease the longitudinal extent of the beam, consequently increasing the current. Presently, one of the popular methods for obtaining the amplification of current in electron beams is by magnetic compression. Magnetic bunch compression is a fairly common tool utilized by the accelerator community, however it can still be considered a stand alone instrument since the details of the physics that affect this type of electron beam manipulation are not categorically well understood. Of particular interest is the coupling between the longitudinal and transverse phase space planes and the forces responsible for the effects that contribute to the dilution of the transverse emittance in the bend plane of the beam. This thesis details the design, construction, simulation, testing and implementation of a magnetic bunch compressor at the Accelerator Test Facility (ATF), a leading photoinjector users' facility located within the Brookhaven National Laboratory (BNL). Simulations show that the magnetic chicane bunch compressor increases the peak current of the ATF electron beam by a significant factor while only sustaining a nominal increase in the bend plane emittance. Additionally, some interesting effects from the inclusion of coherent synchrotron radiation in the simulations such as linearization of the lower energy portion of the beam and smearing of the longitudinal distribution are demonstrated. |
| title: | Development of X-ray Free-electron Lasers |
| journal: | IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, |
| vol-pages: | VOL. 10, NO. 6, p. 1393-1404 |
| year: | 2004 |
| authors: | C. Pellegrini,S. Reiche |
| abstract: | We review and discuss the theoretical and experimental work that has led to the development of short wavelength free-electron lasers operating as single pass amplifiers, starting from the spontaneous undulator radiation, in the self amplified spontaneous emission mode. This work has led to several projects to build this type of free-electron lasers operating at a wavelength of about 0.1 nm, producing coherent X-ray pulses with an unprecedented brilliance and peak power, and pulse length in the femtosecond range. One such project, the LCLS, is presently under construction and is expected to be operational in 2008. |
| title: | Development of a Compact Focusing Solenoid for Photocathode Guns |
| format: | unpublished |
| year: | 1993 |
| authors: | S. Thompson |
| abstract: | A compact solenoid is being developed for the purpose of focusing an electron beam exiting a RF/photocathode electron gun. The size and power consumption of the solenoids in place make a smaller, more efficient solenoid desirable. The present state of this design is shown, including the physical appearance and field profile. |
| title: | Development of an X-Band PWT Photoinjector |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | D. Newsham,Y. Luo,J. Zeng,D. Yu,J. Rosenzweig |
| abstract: | Development of an X-band Plane-Wave-Transformer (PWT), integrated photoinjector continues. Modifications of the end-cell design in this two-section device allow for simultaneous frequency and phase tuning of the accelerating field, thus preventing deceleration at the drift region that separates the two sections. The Los Alamos version of PARMELA is used to determine the expected performance parameters from the final design. |
| title: | Diamagnetic fields due to finite-dimension intense beams in high-gain free-electron lasers |
| journal: | Physical Review E |
| vol-pages: | R2737-40 |
| year: | 1998 |
| authors: | J. Rosenzweig,P. Musumeci |
| abstract: | High-gain, self-amplified spontaneous emission free-electron lasers (SASE FEL's), with proposed operation in wavelengths extending down to X-rays, require intense relativistic electron beams, which under certain conditions can generate large diamagnetic fields. The action of these fields has the potential to seriously degrade FEL performance. It is shown here by both analysis and simulation that the finite size of the electron beams diminishes this effect so that it is negligible for proposed SASE FEL's. . (12 References). |
| title: | Dielectric Wakefield Accelerating Structure as a Source of Terahertz Coherent Cerenkov Radiation |
| conference: | |
| year authored: | 2006 |
| authors: | A.M Cook,J.B Rosenzweig,M.C Thompson,H. Badakov,G. Travish,R. Tikhoplav,O.B Williams,R.J England |
| abstract: | We discuss future experimental work proposed to study the performance of a cylindrical dielectric wakefield accelerating structure as a coherent Cerenkov radiation source at the Neptune laboratory at UCLA. The Cerenkov wakefield acceleration experiment carried out recently by UCLA/SLAC/USC, using the ultrashort and high charge beam (Q = 3 nC, RMS bunch length = 20 micron) at the SLAC FFTB, demonstrated electromagnetic wakes at the few GV/m level. The motivation of our prospective experiment is to investigate the operation of a similar scenario using the comparatively long pulse, low charge beam (Q = 0.5 nC, RMS bunch length = 200 micron) at UCLA Neptune. The field amplitude produced in this setup would be one to two orders of magnitude lower, at the few tens to few 100 MV/m level. Such a decelerating field would extract a significant amount of energy from a low-energy beam in a distance on the order of a few centimeters, allowing the use of short dielectric structures. We discuss details of the geometry and composition of the structures to be used in the experiment. We also examine the possibility of a future dedicated facility at UCLA Neptune based on a hybrid photoinjector currently in development. The intrinsic bunch compression capabilities and improved beam parameters (RMS bunch length = 100 micron, Q = 1 nC) of the photoinjector would allow the creation of a high power radiation source in the terahertz regime. |
| title: | Diffraction radiation defocussing of an electron ring |
| journal: | Nuclear Instruments & Methods |
| vol-pages: | 131-5 |
| year: | 1971 |
| authors: | E. Keil,C. Pellegrini,A. Sessler |
| abstract: | The influence upon axial stability in an electron ring of the diffraction radiation reaction force, generated by a ring moving in an acceleration column, is calculated theoretically. A stability criterion is obtained, and numerical examples show that the criterion is not an important constraint upon the choice of parameters or the operation of an electron ring accelerator. |
| title: | Dynamics of a Driver Beam Propagating in an Underdense Plasma with a Downward Density Transition |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | H. Suk,N. Barov,J. England,E. Esarey,G. Kim,J. Rosenzweig,M. Thompson |
| abstract: | When a short electron beam propagates in an underdense plasma (plasma density n_p < beam density n_b) with a downward density transition, it is known that some background plasma electrons are trapped and accelerated by the plasma wakefield[1]. Beam quality of the trapped plasma electrons is severely affected by the wakefield that is generated by the driving electron beam, so dynamics and instabilities of the driver beam are very important. In this paper, we present some simulation results on the self-trapping and driver beam dynamics. |
| title: | EXPERIMENTAL TESTING OF DYNAMICALLY OPTIMIZED PHOTOELECTRON BEAMS |
| conference: | Erice 2005 |
| year published: | 2006 |
| year authored: | 2005 |
| authors: | J.B ROSENZWEIG,A.M COOK,M. DUNNING,R.J ENGLAND,P. MUSUMECI,M. BELLAVEGLIA,M. BOSCOLO,L. CATANI,A. CIANCHI,G. PIRRO,M. FERRARIO,D. FILLIPETTO,G. GATTI,L. PALUMBO,L. SERAFINI,C. VICARIO,S. JONES |
| abstract: | We discuss the design of and initial results from an experiment in space-charge dominated beam dynamics which explores a new regime of high-brightness electron beam generation at the SPARC (located at INFN-LNF, Frascati) photoinjector. The scheme under study employs the natural tendency in intense electron beams to configure themselves to produce a uniform density, giving a nearly ideal beam from the viewpoint of space charge-induced emittance. The experiments are aimed at testing the marriage of this idea with a related concept, emittance compensation, We show that the existing infrastructure at SPARC is nearly ideal for the proposed tests, and that this new regime of operating photoinjector may be the preferred method of obtaining highest brightness beams with lower energy spread. We discuss the design of the experiment, including developing of a novel time-dependent, aerogel-based imaging system. This system has been installed at SPARC, and first evidence for nearly uniformly filled ellipsoidal charge distributions recorded |
| title: | Effects of Ion Motion in Intense Beam-Driven Plasma Wakefield Accelerators |
| journal: | Physical Review Letters |
| vol-pages: | 95:195002 |
| year: | 2005 |
| authors: | J. Rosenzweig,A. Cook,A. Scott,M. Thompson,R. Yoder |
| abstract: | Recent proposals for using plasma wakefield accelerators (PWFA) as a component of a linear have included intense electron beams with densities many times in excess of the plasma beam’s electric fields expel the plasma electrons from the beam path to many beam radii in We analyze here the motion of plasma ions under the beam fields, and find for a proposed PWFA scenario that the ions completely collapse inside of the beam. Simulations of ion collapse are Implications of ion motion on the feasibility of the PWFA-based colliders are discussed. |
| title: | Effects of the Stray Magnetic Field Caused by a Vacuum Ion Pump on the Accelerator Beamline |
| format: | unpublished |
| year published: | February 2, 1994 |
| year authored: | 1994 |
| authors: | R. Hedrick |
| abstract: | A Vac Ion pump is often used adjacent to the accelerator beamline. Stray magnetic fields are caused by the pump's permanent magnet. The pump is attached to the beamline in one of two configurations, either parallel or perpendicular to the beam path. Moving charged particles, along the beamline, experience a force or kick due to the stray B-field which de3flects the particles away from their original trajectory. From measurements made in each configuration, the deflection angles of the particles were calculated. For a particle of low energy, 4.5 MeV, the angles calculated were approximately 1 and 12 mrad for Config. 1 and Config. 2 respectively. The calculations for high energy, 20 MeV, yielded angles of 1/5 and 3 mrad. These deflections, for Config. 1, are lower than the inherent divergence of the beam, so this configuration can be used without compromising the beam quality. The deflection due to Config. 2, at low energy, is larger than the inherent beam divergence and at high energy, it is over half of the beam divergence angle. the second configuration should not be used. |
| title: | Effects of undulator interruptions on the performance of high-gain FEL amplifiers |
| conference: | 17th International Free Electron Laser Conference |
| year published: | 1996 |
| year authored: | 1995 |
| authors: | K. Kim,M. Xie,C. Pellegrini |
| abstract: | The construction as well as the operation of a long undulator required for short wavelength generation with high-gain free-electron lasers will become easier if the undulator could be interrupted with drift sections every few gain lengths. To evaluate the effect of such interruption on the FEL performance, we study the following three effects; (i) the diffraction loss, (ii) the free space slippage and (iii) the phase de-coherence. The effect (i) is found to be small, the effect (ii) gives a condition on the length of the drift section and the effect (iii) is small, but not negligible. (3 References). |
| title: | Electon Micrographs of Copper Photocathodes |
| format: | |
| year published: | April 1, 1993 |
| year authored: | 1993 |
| authors: | J. Rosenzweig |
| abstract: | Electron micrographs of both the damaged copper photocathode from the initial (September 92/April 93) run, a new unannealed cathode, and the new annealed and polished photocathode were obtained to characterize the photoemitting surfaces. These micrographs were produced by a scanning electron microscope (Cambridge (now owned by Leica) model Stereoscan 250) in the materials science department. The samples were held in place with a stainless steel holder with set screws, which allowed good electrical contact and the ability to rotate the cathodes to large angle with respect to vertical. These micrographs were performed with the idea of quantifying relevant surface features wich could be important in such phenomena as electric field enhancement, anomalous absorption of laser light, and surface plasmon excitation. |
| title: | Electromagnetic Wake-fields and Beam Stability in Slab-symmetric Dielectric Structures |
| format: | preprint |
| year: | 1997 |
| authors: | A. Tremaine,J. Rosenzweig,P. Schoessow |
| abstract: | Several promising schemes for high-gradient acceleration of charged particles in slab-symmetric electromagnetic structures have been recently proposed. In this paper we investigate, by both computer simulation and theoretical analysis, the longitudinal and transverse wake-fields experienced by a relativistic charged particle beam in a planar structure. We show that in the limit of an infinitely wide beam the net deflecting wake-fields vanishes. This result is verified in the limit of a large aspect ratio (sheet) beam by finite beam analysis based on a Fourier decomposition of the current profile, as well as a paraxial wave analysis of the wake-fields driven by Gaussian profile beams. The Fourier analysis forms the basis of an examination of flute instability in the sheet beam system. Practical implications of this result for beam stability and enhanced current loading in short wavelength advanced accelerators are discussed. |
| title: | Electromagnetic wake fields and beam stability in slab-symmetric dielectric structures |
| journal: | Physical Review E |
| vol-pages: | 7204-16 |
| year: | 1997 |
| authors: | A. Tremaine,J. Rosenzweig,P. Schoessow |
| abstract: | Several promising schemes for high-gradient acceleration of charged particles in slab-symmetric electromagnetic structures have been recently proposed. In this paper we investigate, by both computer simulation and theoretical analysis, the longitudinal and transverse wake fields experienced by a relativistic charged particle beam in a planar structure. We show that in the limit of an infinitely wide beam the net deflecting wake fields vanishes. This result is verified in the limit of a large aspect ratio (sheet) beam by finite beam analysis based on a Fourier decomposition of the current profile, as well as a paraxial wave analysis of the wake fields driven by Gaussian profile beams. The Fourier analysis forms the basis of an examination of flute instability in the sheet beam system. Practical implications of this result for beam stability and enhanced current loading in short-wavelength advanced accelerators are discussed. |
| title: | Electron Beam Photocathode Cleaning |
| conference: | APS April Meeting |
| year: | 2000 |
| authors: | M. Thompson,S. Anderson,M. Loh,P. Musumeci,J. Rosenzweig,H. Suk,D. Palmer |
| abstract: | We are experimenting with low energy electron beams as a means of cleaning and improving the quantum efficiency of metallic photocathodes. Electron beam surface cleaning has been used successfully in electron cooling devices at Fermilab (S. Nagaitsev) and Novosibirsk (A.N. Sharapa and A.V. Shemyakin). The cooling device data indicates that a 2 mA h/cm2 specific dose of 3 keV electrons on the surface of the photocathode will produce a surface with an outgas rate at least one order of magnitude lower than a 24 hour 400° C bake achieves. We are currently commissioning a photocathode cleaning "mini-gun" based on a 1 cm2 dispenser cathode to determine how these reduced outgassing rates translate into improvements in quantum efficiency. The mini-gun will be permanently attached to a spare laser port on our 1.6 cell photoinjector gun so that we can clean in situ and on the fly. The cleaning beam will have a large spot size (~5mm) and ample current up to 60 mA at 5 keV. We expect cleaning times on the order of several minutes to achieve a 2 mA h/cm2 specific dose over the interaction region of the photocathode. |
| title: | Electron density enhancement in a quasi isochronous storage ring |
| conference: | 1991 Particle Accelerator Conference |
| year: | 1991 |
| authors: | C. Pellegrini,D. Robin |
| abstract: | Conditions are established for stable single particle motion in a storage ring with very small momentum compaction, and very short bunch length, the quasi isochronous ring. How this condition can be achieved is discussed. Applications of this condition to colliders and synchrotron radiation sources is examined. (2 References). |
| title: | Electron micro-bunch generation from RF photoinjectors |
| conference: | Micro Bunches Workshop |
| year published: | 1996 |
| year authored: | 1995 |
| authors: | L. Serafini,R. Zhang,C. Pellegrini |
| abstract: | In this paper we discuss how the injector specifications of a 2nd-generation plasma beat wave accelerator (PBWA) experiment can be achieved by a photo-injector. Typical required bunch lengths (FWHM) are 50 microns with 15 pC bunch charge. We analyze the possibility of generating such short electron bunches directly from a photoinjector by illuminating a photocathode in an RF electron gun with a phase-locked 160-fs laser pulse. In particular, we address all de-bunching effects taking place during acceleration and transport through the photo-injector. We provide a set of analytical scaling laws, as well as a comparison with detailed simulations of the beam dynamics. The possible performances of the present SATURNUS linac setup are presented, as well as the anticipated capabilities of a multi-cell RF gun structure based on the PWT linac presently in operation at UCLA. (17 References). |
| title: | Emittance Studies of the BNL/SLAC/UCLA 1.6 Cell Photocathode RF Gun |
| conference: | 1997 Particle Accelerator Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | D. Palmer,X. Wang,R. Miller,M. Babzien,I. Ben-Zvi,C. Pellegrini,J. Sheehan,J. Skaritka,H. Winick,M. Woodle,V. Yakimenko |
| abstract: | The symmetrized 1.6 cell S-band photocathode gun developed by the BNL/SLAC/UCLA collaboration is in operation at the Brookhaven Accelerator Test Facility (ATF). A novel emittance compensation solenoid magnet has also been designed, built and is in operation at the ATF. These two subsystems form an emittance compensated photoinjector used for beam dynamics, advanced acceleration and free electron laser experiments at the ATF. The highest acceleration field achieved on the copper cathode is 150 MV/m, and the guns normal operating field is 130 MV/m. The maximum rf pulse length is 3 mu s. The transverse emittance of the photoelectron beam were measured for various injection parameters. The 1 nC emittance results are presented along with electron bunch length measurements that indicated that at above the 400 pC, space charge bunch lengthening is occurring. The thermal emittance, epsilon_0, of the copper cathode has been measured. (7 References). |
| title: | Emittance compensation with dynamically optimized photoelectron beam profiles |
| journal: | Nuclear Instruments and Methods in Physics Research A |
| vol-pages: | 57:87 |
| year: | 2005 |
| authors: | J. Rosenzweig,A. Cook,M. Dunning,M. Ferrario |
| abstract: | Much of the theory and experimentation concerning creation of a high-brightness electron beam from a photocathode, and then applying emittance compensation techniques, assumes that one must strive for a uniform density electron beam, having a cylindrical shape. On the other hand, this shape has large nonlinearities in the space-charge field profiles near the beam’s longitudinal extrema. These nonlinearities are known to produce both transverse and longitudinal emittance growth. On the other hand, it has recently been shown by Luiten that by illuminating the cathode with an ultra-short laser pulse of appropriate transverse profile, a uniform density, ellipsoidally shaped bunch is dynamically formed, which then has linear space-charge fields in all dimensions inside of the bunch. We study here this process, and its marriage to the standard emittance compensation scenario that is implemented in most recent photoinjectors. It is seen that the two processes are compatible, with simulations indicating a very high brightness beam can be obtained. The robustness of this scheme to systematic errors is examined. Prospects for experimental tests of this scheme are discussed. |
| title: | Emittance measurements of the 4.5 MeV UCLA RF photoinjector |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | S. Hartman,N. Barov,S. Park,C. Pellegrini,J. Rosenzweig,G. Travish,R. Zhang,P. Davis,C. Joshi,G. Hairapetian |
| abstract: | The 1.5 cell RF photoinjector has been operated for the past several months using a copper cathode illuminated by 4 ps long pulses of UV (246 nm light, with a variable energy of between 0 to 300 mu J. This typically produces up to 3 nC of charge per bunch. Because space charge forces dominate the electron beam transport a pepper pot measurement system is used to measure the emittance. The emittance is measured as a function of charge, peak accelerating field, laser spot size and initial phase with respect to the RF field. This is accomplished with an automated control and data acquisition system which can measure single shot emittances at a rate of 5 Hz developed at UCLA. The experimental results obtained are then compared with theory and simulations. (4 References). |
| title: | Emittance measurements of the space charge dominated Thomson source photoinjector |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | S. Anderson,J. Rosenzweig,G. Le Sage,J. Crane |
| abstract: | The photocathode rf gun test facility in Livermore National Laboratory's Thomson source is described. The quadrupole scan and slit based emittance measurement techniques are used to measure the emittance of the space charge dominated beam. Experimental results are compared with simulation and theoretical calculations. (10 References). |
| title: | Energy Loss and Accelerating Field in the Plasma Wakefield Accelerator |
| format: | unpublished |
| year: | 2003 |
| authors: | J. Rosenzweig,R. Yoder,N. Barov,M. Thompson |
| abstract: |
| title: | Energy Loss of a High Charge Bunched Electron Beam in Plasma |
| format: | preprint |
| year: | 2000 |
| authors: | N. Barov,J. Rosenzweig,M. Thompson |
| abstract: | There has been much interest in the regime of plasma wake-field acceleration (PWFA) having ultra-high fields, and associated nonlinear plasma motion. With an exact analytical approach, we examine here a fundamental limit of PWFA excitation, by an infinitesimally short relativistic bunched beam. The beam energy loss in this case is shown to be linear in charge even for nonlinear plasma response, where a normalized, unitless charge exceeds unity. The physical basis for this effect is discussed, as are deviations from linear behavior observed in simulations with finite length beams. |
| title: | Energy Loss of a High Charge Bunched Electron Beam in Plasma: Simulation |
| conference: | ICFA Workshop on Physics and Applications of High Brightness Electron Beams |
| year published: | 2003 |
| year authored: | 2002 |
| authors: | J. Rosenzweig,N. Barov,M. Thompson,R. Yoder |
| abstract: |
| title: | Energy Loss of a High Charge Bunched Electron Beam in Plasma: Simulations, Scaling, and Accelerating Wakefields |
| format: | preprint |
| year: | 2003 |
| authors: | J. Rosenzweig,N. Barov,M. Thompson,R. Yoder |
| abstract: |
| title: | Energy Loss of a High Charge Bunched Electron Beam in Plasma: Analysis |
| conference: | ICFA Workshop on Physics and Applications of High Brightness Electron Beams |
| year published: | 2003 |
| year authored: | 2002 |
| authors: | N. Barov,J. Rosenzweig,M. Thompson,R. Yoder |
| abstract: |
| title: | Energy Loss of a High Charge Bunched Electron Beam in Plasma: Analysis |
| format: | preprint |
| year: | 2003 |
| authors: | . |
| abstract: |
| title: | Enhanced Acceleration of Injected Electrons in a Laser Beatwave Induced Plasma Channel |
| format: | preprint |
| year: | 2004 |
| authors: | S. Tochitsky,R. Narang,C. Filip,P. Musumeci,C. Clayton,R. Yoder,K. Marsh,J. Rosenzweig,C. Pellegrini,and Joshi |
| abstract: | Enhanced energy gain of externally injected electrons by a ~3-cm long, high-gradient relativistic plasma wave (RPW) is demonstrated. Using a CO2 laser-beatwave of duration longer than the ion motion time across the laser spot size, a laser self-guiding process is initiated in a plasma channel. Guiding compensates for ionization-induced defocusing (IID) creating a longer plasma, which extends the interaction length between electrons and the RPW. In contrast to a maximum energy gain of 10 MeV when IID is dominant, the electrons gain up to 38 MeV energy in a laser beatwave induced plasma channel. PACS: 52.35Mw, 52.38Hb, 52.38Kd |
| title: | Enhanced resistive wall instability for off-centred beams |
| conference: | 1979 Particle Accelerator Conference |
| year: | 1979 |
| authors: | E. Courant,M. Month,C. Pellegrini,J. Wang |
| abstract: | Beam occupation of a large fraction of the available vacuum chamber typical of high energy proton storage ring designs, results in an enhancement of the resistive wall instability. The effect is considered for ISABELLE during the current stacking procedure. Results for the coasting stack in its initial phase as well as for the injected bunches are presented. (4 References). |
| title: | Envelope Instability in Low-Energy Proton Synchrotrons |
| journal: | Nuclear Instruments & Methods A |
| vol-pages: | 24-30 |
| year: | 1990 |
| authors: | P. Zhou,J. Rosenzweig |
| abstract: | In this paper we investigate the limits on beam intensity in low-energy proton synchrotrons due to the instability of the beam envelope. This instability has been previously examined in the context of space charge dominated ion beams, in particular for inertial confinement fusion applications. We generalize the formalism of beam envelope evolution to include effects found in circular accelerators, i.e. curvature focusing and momentum dispersion. Several example lattices are analyzed to determine intensity limits imposed by onset of envelope instability; it is found that the instability can occur without depressing the phase advance below 90-degrees per cell. |
| title: | Envelope analysis of intense relativistic quasilaminar beams in RF photoinjectors: a theory of emittance compensation |
| journal: | Physical Review E |
| vol-pages: | 7565-90 |
| year: | 1997 |
| authors: | L. Serafini,J. Rosenzweig |
| abstract: | In this paper we provide an analytical description for the transverse dynamics of relativistic, space-charge-dominated beams undergoing strong acceleration, such as those typically produced by RF photoinjectors. These beams are chiefly characterized by a fast transition, due to strong acceleration, from the nonrelativistic to the relativistic regime in which the initially strong collective plasma effects are greatly diminished. However, plasma oscillations in the transverse plane are still effective in significantly perturbing the evolution of the transverse phase space distribution, introducing distortions and longitudinal-transverse correlations that cause an increase in the rms transverse emittance of the beam as a whole. The beam envelope evolution is dominated by such effects and not by the thermal emittance, and so the beam flow can be considered quasilaminar. The model adopted is based on the rms envelope equation, for which we find an exact particular analytical solution taking into account the effects of linear space-charge forces, external focusing due to applied as well as ponderomotive RF forces, acceleration, and adiabatic damping, in the limit that the weak nonlaminarity due to the thermal emittance may be neglected. This solution represents a special mode for beam propagation that assures a secularly diminishing normalized rms emittance and it represents the fundamental operating condition of a space-charge-compensated RF photoinjector. The conditions for obtaining emittance compensation in a long, integrated photoinjector, in which the gun and linac sections are joined, as well as in the case of a short gun followed by a drift and a booster linace, are examined. |
| title: | Envelope description of quasi-laminar beams undergoing reversible emittance transformations |
| conference: | 1996 European Particle Accelerator Conference |
| year published: | 1997 |
| year authored: | 1996 |
| authors: | L. Serafini,J. Rosenzweig |
| abstract: | A fully analytical description is presented for the envelope behavior of intense, space charge dominated beams which are relativistic and quasi-laminar. It is based on a particular solution of the envelope equation for an accelerated beam, which is invariant under reversible emittance transformations: this solution has been termed invariant envelope. The treatment presented in this paper is applicable both to bunched beams in transport lines and in linacs, whenever the beam is space charge dominated. The main interest is in maximizing the beam brightness achievable by Photo-Injectors and preserving the beam quality during the first stages of acceleration. Simple analytical formulae are provided to predict the performances of these devices, when they are operated in the space charge emittance correction regime. (7 References). |
| title: | Envelope instability in the Fermilab Booster |
| conference: | 1991 Particle Accelerator Conference |
| year: | 1991 |
| authors: | P. Zhou,J. Rosenzweig,S. Stahl |
| abstract: | The transverse emittance in the FNAL (Fermi National Accelerator Laboratory) Booster grows at a high beam intensity, in a time less than 100 turns. An examination is made of the possible contributions to the fast emittance growth from coherent instability of the beam envelope. Theoretical analysis, through the use of envelope equations, is employed to predict the dependence of envelope instability on the peak current of the Booster beam. These predictions are compared to the results of multiparticle tracking calculations. (11 References). |
| title: | Experiment to Measure Ramped Electron Bunches at the UCLA Neptune Laboratory Using a Transverse Deflecting Cavity |
| conference: | 12th Advanced Accelerator Concepts Workshop |
| year: | 2006 |
| authors: | R. England,D. Alesini,B. O'Shea,J. Rosenzweig,and Travish |
| abstract: | A proof of principle experiment is underway at the UCLA Neptune laboratory to test the concept of generating linearly ramped relativistic electron bunches (rising in density from head to tail followed by a sharp cutoff) by using a sextupole-corrected dogleg section as a bunch compressor. Bunches with this structure have been predicted to be ideal for use as a plasma wake-field drive beam. The diagnostic being developed to measure the time profile of the beam is an X-Band (9.6 GHz) deflecting cavity. The recently completed cavity is a 9-cell standing wave structure operating in a TM110-like mode, designed to measure the temporal structure of the 2 to 10 ps, 14 MeV electron bunches generated by the Neptune S-band photoinjector and plane-wave transformer (PWT) accelerator beamline, with 50 fs resolution. We discuss the experimental plan for the ramped bunch experiment and present preliminary data related to the tuning and operation of the deflecting cavity. |
| title: | Experimental Characterization of the Saturating, Near Infrared, Self-Amplified Spontaneous Emission Free Electron Laser: Anayasis of Radiation Properties and Electron beam Dynamics |
| format: | thesis |
| year: | 2002 |
| authors: | A. Murokh |
| abstract: | In this work, the main results of the VISA experiment (Visible to Infrared SASE Amplifier) are presented and analyzed. The purpose of the experiment was to build a state-of-the-art single pass self-amplified spontaneous emission (SAS) free electron laser (FEL) based on a high brightness electron beam, and characterize its operation, including saturation, in the near infrared spectral region. This experiment was hosted by Accelerator Test Facility (ATF) at Brookhaven National laboratory, which is a users facility that provides high brightness relativistic electron beams generated with the photoinjector. During the experiment, SASE FEL performance was studied in two regimes: a long bunch, lower gain operation; and a short bunch high gain regime. The transition between the two conditions was possible due to a novel bunch compressionmechanism, which was discovered in teh course of the experiment. This compression allowed the variation fo peak current in teh electron beam before it was launched into the 4-m VISA undulator. In the long bunch regime, a SASE FEL power gain length of 29 cm was obtained, and the generated radiation spectral and statistical properties were characterized. In the short bunch regime, a power gain length of under 18 cm was achieved at 842 nm, which is at least a factor of two shorter than ever previously achieved in this spectral range. Further, FEL saturation was obtained before the undulator exit. The FEL system's performance was measured along the length of the VISA undulator, and in the final state. Statistical, spectral and angular properties of the short bunch SASE radiation have been measured int eh exponential gain regime, and at saturation. One of the most important aspects of the data analysis presented in this thesis was the development and use of start-to-end numerical simulations of the experiment. The dynamics of the ATF electron beam was modeled starting from teh photocathode, through acceleration, transport, and inside the VISA undulator. The model allowed simulation SASE process for different beam conditions, including the effects of the novel bunch compression mechanism on the electron beam 6-D phase space distribution. The numberical simulations displayed an excellent agreement with the experimental data, and became key to understanding cimplex dynamics of the SASE FEL process at VISA. |
| title: | Experimental Demonstration of Wake-Field Effects in Dielectric Structures |
| journal: | Physical Review Letters |
| vol-pages: | 2756-58 |
| year: | 1988 |
| authors: | W. Gai,P. Schoessow,B. Cole,R. Konecny,J. Norem,J. Rosenzweig,J. Simpson |
| abstract: | We have measured the wake fields induced by short, intense relativistic electron bunches in a slow-wave structure consisting of a dielectric-lined tube, as a test of the dielectric wake-field acceleration mechanism. These fields were used to accelerate a second electron bunch which followed the driving bunch at a variable distance. Results are presented for different dielectrics and beam intensities, and are compared with theoretical predictions. |
| title: | Experimental Experience in High Brightness Beams and SASE FELs at UCLA |
| format: | unpublished |
| year published: | June 6, 2002 |
| year authored: | 2002 |
| authors: | J. Rosenzweig |
| abstract: | Outline: Introduction to the UCLA Particle Beam Physics Laboratory (PBPL) High Brightness Beam Generation and Manipulation SASE FELs: Experimental Results Future work at UCLA |
| title: | Experimental Measurement of Nonlinear Plasma Wake-Fields |
| conference: | 1989 Particle Accelerator Conference |
| year: | 1989 |
| authors: | J. Rosenzweig,P. Schoessow,B. Cole,W. Gai,R. Konecny,J. Norem,J. Simpson |
| abstract: | We report direct high resolution observation of nonlinear steepened plasma waves excited in the wake of an intense, self-pinched electron beam. Oscillations in both accelerating and deflecting fields are measured, and analyzed in the context of linear and nonlinear plasma wave theory. The degree of nonlinearity in the wake-fields is shown to be consistent with analytical predictions of the beam self-pinching. The impact of these results on plasma acceleration and focusing schrmrs is discussed. |
| title: | Experimental Requirements for a Self Amplified Spontaneous Emission Test Syste: Design, Construction, Simulation and Analysis of the UCLA High Gain Free Electron Laser |
| format: | thesis |
| year: | 1995 |
| authors: | G. Travish |
| abstract: | This thesis presents the UCLA high gain free electron laser (FEL). FELs have long been proposed as sources of radiation in regimes diffuclt to obtain with conventional lasers. High average power, microwave, far-IR, UV and X-ray are regimes and charactericstics difficult for conventional lasers to achieve. Free Electron Lasers, in principle, do not suffer from the same limitations (atomic transitions, heat dissimpation, thermal lensing, etc.) as atomic and molecular lasers. However, oscillator FELs are still impeded by the need for suitable optics. A high gain FEL, on the other had, requires no oscillator, and can operate in regimes where high quality optics are unavailable. A high gain FEL which requires no input signal, and amplifies the spontaneous emission produced by its own beam is said to operating in the Self Amplified Spontaneous Emission (SASE) mode. A SASE FEL can operate at wavelenghts where no conventional coherent sources are available (i.e., x-rays). High gain FEL experimental work has been very limited, with only a few experiments performed at "optical" wavelengths. No SASE FEL has been operated outside the microwave regime. This work describes an experiment designed to verify the models of high gain FELs, and operate an infrared SASE FEL. High gain FEL theory is reviewed. An analysis of the PBPL FEL is made using analytic as well as numerical models. Experimental effects such as the limited accuracy of beam diagnostics are taken into account. It is show that there are great experimental problems to over come in attempting to determine the preformance and effective start-up level of the PBPL FEL. Some of these difficulties are expected to be shared by future high gain FELs. The PBPL experiment is described with an exphasis on operational problems significant to the FEL. The accelerator, beamline components and diagnostics are described in detail along with design issues and performance parameters. The FEL undulator and optical diagnostics are also described and test data is given. This thesis shows the complexities associated with a high gain FEL, and attempts to determine what can be learned from such an experiment. |
| title: | Experimental and Analytical Study of a High Gain Self Amplified Spontaneous Emission Free Electron Laser Operating in a Large Spectral Bandwidth Regime |
| format: | thesis |
| year: | 2005 |
| authors: | Gerard Andonian |
| abstract: | The drive to create and measure ultra-short pulses in the x-ray regime advances the ongoing development of free electron lasers (FEL). Several proposed schemes, to shorten the pulse length of the radiation, involve driving the FEL with a chirped (linear longitudinal phase space correlation) electron beam in the self amplified spontaneous emission (SASE) mode. This dissertation examines the experiments conducted under such conditions, canvassing analytical and numerical studies of beam dynamics and radiation properties, experimental observations, and descriptions of the development of novel diagnostics. The VISA (Visible-Infrared SASE Amplifier) program has achieved saturation at 840 nm within a 4 m long undulator. A novel bunch compression mechanism during transport was discovered and ultimately responsible for the high peak current required to drive the FEL. Start-to-end simulations, detailing the dynamics from electron beam inception at the photocathode to the FEL radiation properties at the undulator, were successfully benchmarked to observable data. |
| title: | Experimental characterization of nonlinear harmonic radiation from a visible self-amplified spontaneous emission free-electron laser at saturation |
| journal: | Physical Review Letters |
| vol-pages: | 204801 |
| year: | 2002 |
| authors: | A. Tremaine,X. Wang,M. Babzien,I. Ben-Zvi,M. Cornacchia,H. Nuhn,R. Malone,A. Murokh,C. Pellegrini,S. Reiche,J. Rosenzweig,V. Yakimenko |
| abstract: | Nonlinear harmonic radiation was observed using the VISA self-amplified, spontaneous emission (SASE) free-electron laser (FEL) at saturation. The gain lengths, spectra, and energies of the three lowest SASE FEL modes were experimentally characterized. The measured nonlinear harmonic gain lengths and center spectral wavelengths decrease with harmonic number, n, which is consistent with nonlinear harmonic theory. Both the second and third nonlinear harmonics energies are about 1% of the fundamental energy. These experimental results demonstrate for the first time the feasibility of using nonlinear harmonic SASE FEL radiation to produce coherent, femtosecond X-rays. (33 References). |
| title: | Experimental confirmation of transverse focusing and adiabatic damping in a standing wave linear accelerator |
| journal: | Physical Review E |
| vol-pages: | 3572-7 |
| year: | 1997 |
| authors: | S. Reiche,J. Rosenzweig,S. Anderson,P. Frigola,M. Hogan,A. Murokh,C. Pellegrini,L. Serafini,G. Travish,A. Tremaine |
| abstract: | The measurement of the transverse phase-space map, or transport matrix, of a relativistic electron in a high-gradient, radio-frequency linear accelerator (rf linac) at the UCLA photoinjector is reported. This matrix, which indicates the effects of acceleration (adiabatic damping), first-order transient focusing, and ponderomotive second-order focusing, is measured as a function of both rf field amplitude and phase in the linac. The elements of the matrix, determined by observation of centroid motion at a set of downstream diagnostics due to deflections induced by a set of upstream steering magnets, compare well with previously developed analytical theory [J. Rosenzweig and L. Serafini, Phys. Rev. E 49, 1599 (1994)]. The determinant of the matrix is obtained, yielding a direct confirmation of trace space adiabatic damping. Implications of these results on beam optics at moderate energy in high-gradient linear accelerators such as rf photoinjectors are discussed. |
| title: | Experimental demonstration of dynamic focusing of a relativistic electron bunch by an overdense plasma lens |
| journal: | Physical Review Letters |
| vol-pages: | 2403-6 |
| year: | 1994 |
| authors: | G. Hairapetian,P. Davis,C. Clayton,C. Joshi,S. Hartman,C. Pellegrini,T. Katsouleas |
| abstract: | Dynamic focusing of a 3.8 MeV electron bunch, a few collisionless skin depths long approximately 3c/ omega /sub p/, by an overdense, thick plasma lens has been demonstrated. Because of electron inertial effects, the head of the bunch is virtually unaffected by the lens while the rest is focused to varying degree. Time-resolved measurements performed 31 cm downstream of the plasma lens show that, in time, the bunch pinches from an initial size of 2.7 mm (FWHM) to about 0.57 mm and then expands, in reasonable agreement with theory. (20 References). |
| title: | Experimental demonstration of plasma lens focusing |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | G. Hairapetian,P. Davis,C. Clayton,C. Joshi,S. Hartman,C. Pellegrini,T. Katsouleas |
| abstract: | The magnetic self-focusing of a relativistic electron beam propagating through a plasma is demonstrated. The plasma which is produced by an RF discharge in a glass tube with no externally applied magnetic field focuses a 3.5 MeV, 25 ps (FWHM) long electron beam from an initial size of 2.5 mm (FWHM) to about 0.5 mm (FWHM) at a focal length of 18 cm. (7 References). |
| title: | Experimental measurement of high-gradient standing wave accelerator transport matrix |
| conference: | 1997 Particle Accelerator Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | S. Reiche,J. Rosenzweig,L. Serafini |
| abstract: | This paper presents an experimental study of the transverse beam dynamics of an electron beam in a high-gradient, standing wave linear accelerator. A 3.6 MeV beam from the UCLA RF Photoinjector (SATURNUS) is injected at various phases and rf field amplitudes into the plane wave transformer (PWT) linac (peak acceleration 40 MeV/m), and its transverse dynamics measured by a corrector magnet sweeping method. This method allows us to reconstruct the transverse matrix elements, which are compared to analytical predictions (J.B. Rosenzweig and L. Serafini, Physical Review E 49, 1599 (1994)). The determinant of the experimentally derived matrix is found to be the ratio of the initial to final momentum, verifying the theory, and providing direct evidence of adiabatic damping of transverse trace space. (9 References). |
| title: | Experimental measurement of nonlinear plasma wake fields |
| journal: | Physical Review A |
| vol-pages: | 1586-89 |
| year: | 1989 |
| authors: | J. Rosenzweig,P. Schoessow,B. Cole,W. Gai,R. Konecny,J. Norem,J. Simpson |
| abstract: | We report direct high-resolution observation of nonlinear steepened plasma waves excited in the wake of an intense, self-pinched electron beam. Oscillations in both accelerating and deflecting fields are measured, and analyzed in the context of linear and nonlinear plasma-wave theory. The degree of nonlinearity in the wake fields is shown to be consistent with analytical predictions of the beam self-pinching. The impact of these results on plasma acceleration and focusing schemes is discussed. |
| title: | Experimental non linear beam dynamics studies with a turn-by-turn phase space monitor at SPEAR |
| conference: | ICFA Workshop on Nonlinear and Collective Phenomena in Beam Physics |
| year published: | 1999 |
| year authored: | 1998 |
| authors: | A. Terebilo,C. Pellegrini,M. Cornacchia |
| abstract: | About 10 years ago the possibility of using turn-by-turn phase beam position monitors to gain insight into phase space dynamics of a single particle in a storage ring raised some interest among accelerator physicists. It was soon argued that Landau damping and collective effects would seriously complicate the interpretation of data. We have established that in SPEAR it is possible to lock a single bunch into a collective 'rigid body' mode. When in this mode the bunch will behave similar to a super particle of finite size with the charge equal to that of the bunch. In this paper we report on experiments that demonstrate this effect. We also numerically study the strong coupling limit, in which the transition to 'rigid body' motion occurs, for the two models proposed earlier. We present the experiments on non-linear resonance crossing and frequency map measurement in the 'super particle' framework. (11 References). |
| title: | Experimental nonlinear beam dynamics studies at SPEAR |
| conference: | 1997 Particle Accelerator Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | A. Terebilo,C. Pellegrini,M. Cornacchia,J. Corbett,D. Martin |
| abstract: | The frequency map analysis of a Hamiltonian system recently introduced to accelerators physics in combination with turn-by-turn phase space measurements opens new experimental opportunities for studying nonlinear dynamic in storage rings. In this paper we report on the experimental program at SPEAR having the goal of measuring the frequency map of the machine. In this paper we discuss the accuracy of the instantaneous tune extraction from experimental data and demonstrate the possibility of frequency map measurement. (7 References). |
| title: | Experimental observation of plasma wake-field acceleration |
| journal: | Physical Review Letters |
| vol-pages: | 98-101 |
| year: | 1988 |
| authors: | J. Rosenzweig,D. Cline,B. Cole,H. Figueroa,W. Gai,R. Konecny,J. Norem,P. Schoessow,J. Simpson |
| abstract: | The authors report the first experimental test of the physics of plasma wake-field acceleration performed at the Argonne National Laboratory Advanced Accelerator Test Facility. Megavolt-per-meter plasma wake fields are excited by a intense 21-MeV, multipicosecond bunch of electrons in a plasma of density n/sub e/ approximately=10/sup 13/ cm/sup -3/, and probed by a low-intensity 15-MeV witness pulse with a variable delay time behind the intense bunch. Accelerating and deflecting wake-field measurements are presented, and the results compared to theoretical predictions. (8 References). |
| title: | Experimental studies of plasma wake-field acceleration and focusing |
| journal: | Physica Scripta |
| vol-pages: | 110-21 |
| year: | 1990 |
| authors: | J. Rosenzweig,B. Cole,C. Ho,W. Gai,R. Konecny,S. Mtingwa,J. Norem,M. Rosing,P. Schoessow,J. Simpson |
| abstract: | The Plasma Wake-field Accelerator (PWFA) continues to be the object of much investigation, due to the promise of the ultra-high accelerating gradients that can exist in relativistic plasma waves driven in the wake of charged particle beams. These large amplitude plasma wake-fields are of interest in the laboratory, both for the wealth of basic nonlinear plasma wave phenomena which can be studied, as well as for the applications of acceleration and focusing of electrons and positrons in linear colliders. Plasma wake-field waves are also of importance in nature, due to their possible role in direct cosmic ray acceleration. The purpose of the present work is to review the experimental advances made in PWFA research at Argonne National Laboratory, in which many interesting beam and plasma phenomena have been observed. Emphasis is given to discussion of the nonlinear aspects of the PWFA beam-plasma interaction. (29 References). |
| title: | Experimental testing of the TTF RF photoinjector |
| conference: | 1997 Particle Accelerator Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | E. Colby,M. Conde,J. Rosenzweig,P. Colestock,H. Edwards,K. Koepke,F. Nezrick |
| abstract: | Results from the experimental testing of the prototype TESLA Test Facility (TTF) RF photoinjector are summarized. Preliminary measurements of the performance of the injector indicate that, with refinement, the design values for the transverse emittances (20 x 20 pi mm-mr) are not unrealistic, with uncompressed transverse emittances of 40 pi mm mr having been obtained under somewhat less ideal circumstances than those simulated. Preliminary pulse length measurements with and without the pulse compressor suggest pulse compression, but further study is required. |
| title: | Exponential gain and saturation of a self-amplified spontaneous emission free-electron laser |
| journal: | Science |
| vol-pages: | 2037-41 |
| year: | 2001 |
| authors: | S. Milton,E. Gluskin,N. Arnold,C. Benson,W. Berg,S. Biedron,M. Borland,Y. Chae,R. Dejus,M. Den Hartog,B. Deriy,M. Erdmann,Y. Eidelman,M. Hahne,Z. Huang,K. Kim,J. Lewellen,Y. Li,A. Lumpkin,O. Makarov,E. Moog,A. Nassiri,V. Sajaev,R. Soliday,B. Tieman,E. Trakhtenberg,G. Travish,I. Vasserman,G. Wiemerslage,B. Yang,N. Vinokurov,X. Wang |
| abstract: | Self-amplified spontaneous emission in a free-electron laser has been proposed for the generation of very high brightness coherent X-rays. This process involves passing a high-energy, high-charge, short-pulse, low-energy-spread, and low-emittance electron beam through the periodic magnetic field of a long series of high-quality undulator magnets. The radiation produced grows exponentially in intensity until it reaches a saturation point. We report on the demonstration of self-amplified spontaneous emission gain, exponential growth, and saturation at visible (530 nanometers) and ultraviolet (385 nanometers) wavelengths. Good agreement between theory and simulation indicates that scaling to much shorter wavelengths may be possible. These results confirm the physics behind the self-amplified spontaneous emission process and forward the development of an operational X-ray free-electron laser. (30 References). |
| title: | Extended version of an S-band RF gun |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | S. Park,C. Pellegrini |
| abstract: | A 4.5 MeV RF gun has been in operation at UCLA as a part of a 20 MeV linac. To improve the photoelectron beam parameters without changing the major characteristics of the driving laser and RF systems, a revised and extended version of the present RF gun has been investigated. The new gun consists of 6 full cells terminated at either end by one half cell each. The gun operates in pi -mode at 2.856 GHz. Accelerating fields and mode structures have been studied, and based on this, particle dynamics has been simulated. An aluminum prototype has been built for cold tests. Description of the gun is presented along with initial computational and experimental results. (10 References). |
| title: | Faraday Cup Beam Dumps for the UCLA PBPL |
| format: | tech note |
| year published: | May 16, 1994 |
| year authored: | 1994 |
| authors: | D. McIntosh |
| abstract: | Two identical Faraday cups have been designed and built to stop a 20 meV, 1 nC electron pulse beam, accelerated at the UCLA Particle Beam Physics Laboratory (PBPL). The dumps were also designed to serve as charge measuring diagnostics. Each device is a simple design using a carbon graphite core, Delrin insulation, vacuum tubing components, and lead brick shielding. The graphite core stops the beam while producing manageable secondary radiation sources. The overall design considerations and final solutions are summarized. |
| title: | Feasibility study of a storage ring for a high-power XUV free-electron laser |
| journal: | Particle Accelerators |
| vol-pages: | 223-66 |
| year: | 1986 |
| authors: | J. Bisognano,S. Chattopadhyay,M. Cornacchia,A. Garren,K. Halbach,A. Jackson,K. Kim,H. Lancaster,J. Peterson,M. Zisman,C. Pellegrini,G. Vignola |
| abstract: | A high-gain free-electron lase (FEL), operating in a special by-pass of a storage ring, can provide tens of megawatts of coherent power at wavelengths shorter than 1000 AA. The requirements on beam quality are demanding-a few hundred amperes of peak current in an emittance of about 10/sup -8/ m-rad with a relative energy spread of about 10/sup -3/. Designing an electron storage ring with the required characteristics involves a comprehensive analysis of the restrictions arising from, and relationships between, the FEL physics, the multiparticle beam phenomena, and the ring lattice structure. A summary of such a study is reported and some design examples are given. (39 References). |
| title: | Field Measurements of the Steering Magnets |
| format: | tech note |
| year: | 1993 |
| authors: | J. Caulfield |
| abstract: | On Axis field measurements were made for the steering magnets with the current ranging from -1- to +10 Amps. The filed produced is linear with current. Some hysteresis is present. The first and second field integrals are also linear with current (as expected) and also show some hysteresis. The field produced ranges from about +/- 130 Gauss for +/- 10 Am,p with an effective field length of 9.75cm. |
| title: | Final focusing and enhanced disruption from an underdense plasma lens in a linear collider |
| journal: | Physical Review D |
| vol-pages: | 923?926 |
| year: | 1989 |
| authors: | P. Chen,S. Rajagopalan,J. Rosenzweig |
| abstract: | In this work we examine the viability of employing an underdense plasma lens as a final focusing method for a linear e+e- collider. The underdense plasma lens is superior to the overdense lens in that it improves focusing linearity and background event rate, but works well only for electrons. We thus consider the interaction of an e- beam which is smaller than the e+ beam at collision, a case we term "bootstrap disruption." The potential luminosity enhancement is determined by analysis of the lens optics and simulation of the bootstrap disruption. |
| title: | First Observation of Luminosity-Driven Extraction Using Channeling with a Bent Crystal |
| format: | preprint |
| year: | 1998 |
| authors: | A. Asseev,S. Baker,S. Bogacz,R. Biryukov,R. Carrigan,D. Chen,D. Cline,B. Cox,J. Ellison,W. Gabella,V. Golovatyuk,G. Jackson,A. Khanzadeev,A. McManus,N. Mokhov,C. Murphy,B. Newberger,T. Prokofieva,S. Ramachandran,J. Rhoades, Rosenzweig,V. Samsonov,H. Shih,G. Solodov,A. Tartin,E. Tsyganov |
| abstract: | Luminosity-driven channeling extraction has been observed for the first time from a 900 GeV circulating proton beam at the Fermilab Tevatron. The extraction efficiency was found to be of he order of 30%. A 150 kHz beam was obtained during luminosity-driven extraction with a tolerable background rate at the collider experiments, and a 900 kHz beam was obtained when background limits were doubled. This is the highest energy at which channeling has been observed. |
| title: | First observation of luminosity-driven extraction using channeling with a bent crystal |
| journal: | Physical Review Special Topics-Accelerators & Beams |
| vol-pages: | 022801 |
| year: | 1998 |
| authors: | R. Carrigan,D. Chen,G. Jackson,N. Mokhov,C. Murphy,S. Baker,S. Bogacz,D. Cline,S. Ramachandran,J. Rhoades,J. Rosenzweig,A. Asseev,R. Biryukov,A. Taratin,J. Ellison,A. Khanzadeev,T. Prokofieva,V. Samsonov,G. Solodov,B. Newberger,E. Tsyganov,H. Shih,W. Gabella,B. Cox,V. Golovatyuk,A. McManus |
| abstract: | Luminosity-driven channeling extraction has been observed for the first time using a 900 GeV circulating proton beam at the superconducting Fermilab Tevatron. The extraction efficiency was found to be about 30%. A 150 kHz beam was obtained during luminosity-driven extraction with a tolerable background rate at the collider experiments. A 900 kHz beam was obtained when the background limits were doubled. This is the highest energy at which channeling has been observed. |
| title: | First results from bent crystal extraction at the Fermilab Tevatron |
| journal: | Nuclear Instruments & Methods B |
| vol-pages: | 231-238 |
| year: | 1996 |
| authors: | C. Murphy,R. Carrigan,D. Chen,G. Jackson,N. Mokhov,H. Shih,B. Cox,V. Golovatyuk,A. McManus,A. Bogacz,D. Cline,S. Ramachandran,J. Rhoades,J. Rosenzweig,B. Newberger,J. Ellison,S. Baker,C. Sun,W. Gabella,E. Tsyganov,A. Taratin,A. Asseev,V. Biryukov,A. Khanzadeev,T. Prokofieva,V. Samsonov,G. Solodov |
| abstract: | First results from Fermilab Experiment 853 are presented. E853 is an experiment to test the feasibility and efficiency of extracting a low-intensity beam from the halo of the Tevatron using channeling in a bent silicon crystal. The motivation of the experiment is to apply crystal extraction to trans-TeV accelerators like the LHC. Extensive simulation work has been carried out. Two accelerator operating modes have been developed for crystal studies, ''kick'' mode and diffusion mode. Results from the first successful extraction in kick mode are presented. |
| title: | First results of the Fermilab high-brightness RF photoinjector |
| conference: | 1999 Particle Accelerator Conference |
| year: | 1999 |
| authors: | J. Carneiro,R. Carrigan,M. Champion,P. Colestock,H. Edwards,J. Fuerst,W. Hartung,K. Koepke,M. Kuchnir,J. Santucci,L. Spentzouris,M. Fitch,A. Melissinos,P. Michelato,C. Pagani,D. Sertore,N. Barov,J. Rosenzweig |
| abstract: | A collaboration has been formed between FNAL, UCLA, LNFN Milano, the University of Rochester, and DESY to develop the technology of an RF photoinjector, followed by a superconducting cavity, to produce high bunch charge (8 nC) with low normalized emittance ([left angle bracket]20 mm mrad) in bunch spacing trains of 800 bunches separated by mu s. The activities of bunch charge the collaboration fall into two categories: 1. the development of Injector II for the TeSLA/TTF accelerator. This photoinjector (TTF RF Gun) was tested at Fermilab in September and October 1998 and installed at DESY in November 1998. 2. the installation at the A0 Hall of Fermilab of a modified version of the TTF photoinjector, for photoinjector R&D and to study novel applications of high-brightness, pulsed electron beams. This photoinjector (A0 RF Gun) produced its first beam in March 1999. This paper presents a summary of the tests done at Fermilab on the TITF Injector II and the first results obtained on the new Fermilab photoinjector. |
| title: | Flat-beam RF photocathode sources for linear collider applications |
| conference: | 1991 Particle Accelerator Conference |
| year: | 1991 |
| authors: | J. Rosenzweig |
| abstract: | Laser-driven RF photocathodes represent a recent advance in high-brightness electron beam sources. The author investigates a variation on these devices that was obtained by using a ribbon laser pulse to illuminate the cathode, yielding a flat beam ( sigma /sub x/[right angle bracket][right angle bracket] sigma /sub y/) which has asymmetric emittances at the cathode proportional to the beam size in each transverse dimension. The flat-beam geometry mitigates space charge forces which lead to intensity-dependent transverse and longitudinal emittance growth, thus limiting the beam brightness. The fundamental limit on achievable emittance and brightness is set by the transverse momentum distribution and peak current density of the photoelectrons. (11 References). |
| title: | Focusing of a Relativistic Electron Beam by an Underdense Plasma Lens |
| format: | unpublished |
| year: | 1994 |
| authors: | P. Davis,G. Hairapetian,C. Clayton,C. Joshi,C. Pellegrini |
| abstract: | Plasma Lenses produce focusing gradients exceeding those of conventional quadrupole magnets by several orders of magnitude. We have recently observed dynamic focusing by an overdense plasma lens [G. Hairapetian, et al., Phys.Rev.Lett. 72, 2403 (1994)]. Theoretically, an underdense plasma lens could offer several advantages over the overdense lens: ... |
| title: | Free electron laser experiment at the NSLS 700 MeV electron storage ring |
| conference: | 1981 Particle Accelerator Conference |
| year: | 1981 |
| authors: | J. Blewett,L. Blumberg,A. Campillo,R. DiNardo,H. Hsieh,S. Krinsky,A. Luccio,C. Pellegrini,J. Schuchman,P. Takacs,A. van Steenbergen |
| abstract: | A free electron laser experiment is described, to be performed with the 700 MeV electron storage ring of the National Synchrotron Light Source. The experiment is designed to study the parameters of the fel in an electron storage ring and the performance of this laser as a source of short wavelength radiation in the VUV region of the spectrum. The initial experiment will be carried out at a wave length of approximately 3000 AA, utilizing a permanent magnet undulator. For an average electron current of 1 A distributed in three beam bunches, the small signal gain per pass (relative enhancement of the radiation intensity per electron bunch pass through the undulator) is calculated to be approximately 10%. (11 References). |
| title: | Free electron lasers for the XUV spectral region |
| conference: | 6th International Free Electron Laser Conference |
| year published: | 1985 |
| year authored: | 1984 |
| authors: | J. Murphy,C. Pellegrini |
| abstract: | The generation of high intensity coherent radiation in the soft X-ray region from a free electron laser will require the FEL to operate in the high gain or collective instability regime. In this mode of operation, which does not require a cavity resonator, the radiation field grows exponentially along the undulator until nonlinear effects bring on saturation. The authors discuss the conditions that the electron beam and the undulator must satisfy for the collective instability to develop. They present an example of an electron storage ring with an undulator in a bypass section which satisfies these conditions. They present estimates of the output power that one can expect from such systems. (25 References). |
| title: | Free electron lasers: development and applications |
| conference: | 14th International Conference on High Energy Accelerators |
| year published: | 1990 |
| year authored: | 1989 |
| authors: | C. Pellegrini |
| abstract: | The author gives an overview of the FEL status and applications; discusses some of the work being done for its further development, in particular in the soft X-ray region. (69 References). |
| title: | Free-Electron Lasers as Pumps for High-Energy Solid-State Lasers |
| conference: | 25th International Free Electron Laser Conference |
| year published: | 2004 |
| year authored: | 2003 |
| authors: | G. Travish,J. Crane,A. Tremaine |
| abstract: | High average-power free-electron lasers may be useful for pumping high peak-power solid-state laser-amplifiers. At very high peak-powers, the pump source for solid-state lasers is non-trivial: flash lamps produce thermal problems and are unsuitable for materials with short florescence-times, while diodes can be expensive and are only available at select wavelengths. FELs can provide pulse trains of light tuned to a laser material's absorption peak, and florescence lifetime. An FEL pump can thus minimize thermal effects anad potentially allow for new laser materials to be used. This paper examines the design of a high average-power, effecient high-gain FEL for use as a pump source. Specifically, the cases of a 100 J class pump, and a 100 TW-class laser at a planned fourth-generation light-source are considered. |
| title: | Free-Electron Simulations at Short Wavelengths |
| format: | unpublished |
| year published: | May 01, 2002 |
| year authored: | 2002 |
| authors: | S. Reiche |
| abstract: | Outline: FEL Simulations Overview Codes Shot-Noise Models Short Wavelength Effects Spontaneous Radiation Wake Fields Undulator Description Start-End Simulations |
| title: | Fundamental and Harmonic Microbunching Measurements in a High-Gain, Self-Amplified, Spontaneous Emission Free-Electron Laser |
| format: | preprint |
| year: | 2002 |
| authors: | A. Tremaine,X. Wang,M. Babzien,I. Ben-Zvi,M. Cornacchia,A. Murokh,H. Nuhn,R. Malone,C. Pellegrini,S. Reiche,J. Rosenzweig,J. Skaritka,V. Yakimenko |
| abstract: | The self-amplified, spontaneous emission free-electron laser (SASE-FEL) gain process is a collective instability which induces microbunching in the electron beam. Micro-bunching approaching unity at the fundamental FEL wavelength (845 nm), and its second harmonic, have been measured at the VISA FEL, at or near saturation. These measurements, which use the beam's coherent transition radiation (CTR) spectrum, are sompared to the predictions of FEL simulations. Comparison of shot-by-shot SASE and CTR signals firmly establishes the role of SASE in the development of microbunching harmonics. |
| title: | Fundamental and harmonic microbunching in a high-gain self-amplified spontaneous-emission free-electron laser |
| journal: | Physical Review E |
| vol-pages: | 036503 |
| year: | 2002 |
| authors: | A. Tremaine,X. Wang,M. Babzien,I. Ben-Zvi,M. Cornacchia,A. Murokh,H. Nuhn,R. Malone,C. Pellegrini,S. Reiche,J. Rosenzweig,J. Skaritka,V. Yakimenko |
| abstract: | Electron beam microbunching in both the fundamental and second harmonic in a high-gain self-amplified spontaneous emission free-electron laser (SASE FEL) was experimentally characterized using coherent transition radiation. The microbunching factors for both modes (b1 and b2) approach unity, an indication of FEL saturation. These measurements are compared to the predictions of FEL simulations. The simultaneous capture of the microbunching and SASE radiation for individual micropulses correlate the longitudinal electron beam structure with the FEL gain. |
| title: | GENESIS 1.3: a fully 3D time-dependent FEL simulation code |
| conference: | 20th International Free Electron Laser Conference |
| year published: | 1999 |
| year authored: | 1998 |
| authors: | S. Reiche |
| abstract: | Numerical simulation codes are basic tools for designing Free Electron Lasers (FEL). They are used to study the impact of different parameters, e.g. wiggler errors and external focusing, which allow FEL users to optimize the performance. For faster execution some simulation codes assume radial symmetry or decompose the radiation field into a few azimuthal modes, although then this treatment does not include the full description of the FEL. This contribution describes the new FEL code GENESIS 1.3 which uses a fully three-dimensional representation of the FEL equations in the paraxial approximation for time-dependent and steady-state simulations of single-pass FEL. In particular this approach is suitable for cases where the radial symmetry is broken by the electron beam distribution as well as by wiggler errors, betatron motion and off axis injection of the electron beam. The results, presented here, are based on the parameters of the TESLA Test Facility FEL at DESY. |
| title: | Gain Computation |
| format: | unpublished |
| year published: | April 24, 2002 |
| year authored: | 2002 |
| authors: | S. Reiche |
| abstract: |
| title: | Generation of High Brightness X-Rays with the PLEIADES Thomson X-Ray Source |
| conference: | 2003 Particle Accelerator Conference |
| year: | 2003 |
| authors: | W. Brown,S. Anderson,C. Barty,J. Crane,R. Cross,D. Fittinghoff,F. Hartemann,J. Kuba,G. Le Sage,D. Slaughter,P. Springer,A. Tremaine,J. Rosenzweig,D. Gibson |
| abstract: | The use of short laser pulses to generate high peak intensity, ultra-short x-ray pulses enables exciting new experimental capabilities, such as femtosecond pump-probe experiments used to temporally resolve material structural dynamics on atomic time scales. PLEIADES (Picosecond Laser Electron InterAction for the Dynamic Evaluation of Structures) is a next generation Thomson scattering x-ray source being developed at Lawrence Livermore National Laboratory (LLNL). Ultra-fast picosecond x-rays (10-200 keV) are generated by colliding an energetic electron beam (20-100 MeV) with a high intensity, sub-ps, 800 nm laser pulse. The peak brightness of the source is expected to exceed 1020 photons/s/0.1 bandwidth/mm2/mrad2. Simulations of the electron beam production, transport, and final focus are presented. Electron beam measurements, including emittance and final focus spot size are also presented and compared to simulation results. Measurements of x-ray production are also reported and compared to theoretical calculations. |
| title: | Generation of high-intensity coherent radiation in the soft-X-ray and vacuum-ultraviolet region |
| journal: | Journal of the Optical Society of America B-Optical Physics |
| vol-pages: | 259-64 |
| year: | 1985 |
| authors: | J. Murphy,C. Pellegrini |
| abstract: | An electron beam can be made to interact with an undulator magnet so that a collective unstable mode is excited. In this mode, the beam generates coherent radiation whose wavelength is determined by the undulator period and the electron energy. By proper choice of the electron-beam energy, energy dispersion, and density, one can obtain coherent radiation in the soft-X-ray region with peak and average power of the order of hundreds of megawatts and hundreds of milliwatts, respectively. Larger peak powers, of the order of a gigawatt, can be expected for UV radiation with lambda in the range of 500-2000 AA. The authors discuss the physical principles of these systems and give examples of how they might be built. (14 References). |
| title: | Generation of sub-picosecond electron bunches from RF photoinjectors |
| journal: | Nuclear Instruments & Methods A |
| vol-pages: | 305-14 |
| year: | 1997 |
| authors: | L. Serafini,R. Zhang,C. Pellegrini |
| abstract: | In this paper we discuss the possibility to generate sub-picosecond electron bunches directly from a photoinjector by illuminating a photo-cathode in an RF cavity with a phase-locked sub-picosecond laser pulse. In particular, we address all de-bunching effects taking place during acceleration and transport through a photoinjector. We provide analysis of the beam dynamics, as well as the comparison with numerical simulations. The possible performances of the present SATURNUS linac setup are presented, as well as the anticipated capabilities of a multi-cell RF gun structure based on the PWT linac presently in operation at UCLA. (23 References). |
| title: | HOMDYN study for the LCLS RF photo-injector |
| conference: | 2nd ICFA Advanced Accelerator Workshop on the Physics of High Brightness Beams |
| year published: | 2000 |
| year authored: | 1999 |
| authors: | M. Ferrario,J. Clendenin,D. Palmer,J. Rosenzweig,L. Serafini |
| abstract: | We report the results of a recent beam dynamics study, motivated by the need to redesign the LCLS photoinjector, that led to the discovery of a new effective working point for a split RF photoinjector. The HOMDYN code, the main simulation tool adopted in this work, is described together with its recent improvements. The new working point and its LCLS application is discussed. Validation tests of the HOMDYN model and low emittance predictions, 0.3 mm-mrad for a 1 nC flat top bunch, are performed with respect to the multi-particle tracking codes ITACA and PARMELA. (26 References). |
| title: | Hamiltonian model of a free electron laser |
| journal: | Optics Communications |
| vol-pages: | 55-60 |
| year: | 1987 |
| authors: | R. Bonifacio,F. Casagrande,C. Pellegrini |
| abstract: | Both the Compton and the Raman regimes of a free electron laser are described by a relativistic Hamiltonian which originates the evolution equations for 2N+2 canonically conjugate electron and field variables, with the space coordinate as the independent variable. Space charge and field contribution to electron transverse velocity are included. Scaled variables are introduced which allow for a description of the behaviour of the system in terms of a single electron-beam parameter. (16 References). |
| title: | High Brightness Symmetric Emittance RF Photoinjector Preliminary Design Report |
| format: | unpublished |
| year published: | September 15, 1994 |
| year authored: | 1994 |
| authors: | E. Colby,J. Ostiguy,J. Rosenzweig |
| abstract: | A preliminary design for a high bunch charge (8 nC), low emittance (> 20 mm-mr) radiofrequency electron photoinjector matched to the requirements of the Tesla Test Facility is presented. A 1.5 cell iris coupled pi-mode structure with high average accelerating gradient is chosen for its high shunt impedance, simplicity, and ability to accommodate an externally mounted solenoid for simultaneous beam divergence control an demittance compensation. Beam optics are optimized for an overall injector consisting of the electron gun followed by one linac capture section, a dipole chicane for magnetic bunch compression to achieve a bunch length corresponding to sigma_z = 1 mm. Electrical and beam dynamical aspects of the photoinjector design are presented. A description of the proposed experimental program is included. |
| title: | High Energy Gain of Trapped Electrons in a Tapered, Diffraction-Dominated Inverse-Free-Electron Laser |
| format: | preprint |
| year: | 2005 |
| authors: | P. Musumeci,S. Tochitsky,S. Boucher,C. Clayton,A. Doyuran,R. England,C. Joshi,C. Pellegrini,J. Ralph,J. Rosenzweig,C. Sung,S. Tolmachev,G. Travish,A. Varfolomeev,A. Jr.,T. Yarovoi,R. Yoder |
| abstract: | Energy gain of trapped electrons in excess of 20 MeV has been demonstrated in an Inverse-Free- Electron-Laser (IFEL) accelerator experiment. A 14.5 MeV electron beam is copropagated with a 400 GW CO2 laser beam in a 50 cm long undulator strongly tapered in period and ¯eld amplitude. The Rayleigh range of the laser, » 1.8 cm, is much shorter than the undulator length yielding a di®raction-dominated interaction. Experimental results on the dependence of the acceleration on injection energy, laser focus position, and laser power are discussed. Simulations, in good agreement with the experimental data, show that most of the energy gain occurs in the ¯rst half of the undulator at a gradient of 70 MeV/m and that the structure in the measured energy spectrum arises because of higher harmonic IFEL interaction in the second half of the undulator. |
| title: | High Energy Gain of Trapped Electrons in a Tapered, Diffraction-Dominated Inverse-Free-Electron Laser |
| journal: | Physical Review Letters |
| vol-pages: | 94:154801 |
| year: | |
| authors: | P. Musumeci,S.Ya Tochitsky,S. Boucher,C. Clayton,A. Doyuran,R. England,C. Joshi,C. Pellegrini,J. Ralph,J. Rosenzweig,C. Sung,S. Tolmachev,G. Travish,A. Varfolomeev,A. Jr.,T. Yarovoi,R. Yoder |
| abstract: | Energy gain of trapped electrons in excess of 20 MeV has been demonstrated in an inverse-freeelectron- laser (IFEL) accelerator experiment. A 14.5 MeVelectron beam is copropagated with a 400 GW CO2 laser beam in a 50 cm long undulator strongly tapered in period and field amplitude. The Rayleigh range of the laser, 1:8 cm, is much shorter than the undulator length yielding a diffraction-dominated interaction. Experimental results on the dependence of the acceleration on injection energy, laser focus position, and laser power are discussed. Simulations, in good agreement with the experimental data, show that most of the energy gain occurs in the first half of the undulator at a gradient of 70 MeV=m and that the structure in the measured energy spectrum arises because of higher harmonic IFEL interaction in the second half of the undulator. |
| title: | High brightness electron sources |
| conference: | 1998 Linear Accelerator Conference |
| year: | 1998 |
| authors: | J. Rosenzweig |
| abstract: | The production of unprecedentedly high brightness electron beams is a critical aspect of many applications, from free-electron lasers to advanced accelerators. The preferred method for obtaining these beams is the radiofrequency photoinjector. The physics and technology aspects of this device are reviewed here, along prospects for future progress in high-brightness beam development. |
| title: | High power femtosecond pulses from an X-ray SASE-FEL |
| conference: | 21st International Free Electron Laser Conference |
| year published: | 2000 |
| year authored: | 1999 |
| authors: | C. Pellegrini |
| abstract: | We discuss how to use the large-gain bandwidth of an X-ray SASE-FEL to produce femtosecond long pulses by chirping and compressing the output FEL radiation. We consider the power level, spectral width, and intensity fluctuations of the compressed X-ray pulse compared to the case with no compression. (9 References). |
| title: | High-Brightness Beam Generation and Characterization at the Advanced Photon Source Low-Energy Undulator Test Line Linac |
| conference: | APS April Meeting |
| year: | 2000 |
| authors: | J. Lewellen,S. Biedron,M. Borland,M. Hahne,K. Harkay,A. Lumpkin,S. Milton,N. Sereno,G. Travish |
| abstract: | Improvements to the Advanced Photon Source injector linac have been made to allow for the production and characterization of high-brightness beams in support of fourth-generation light source research. In particular, effort has been directed at generating beams suitable for use in the low-energy undulator test line (LEUTL) free-electron laser (FEL). We describe the enhancements to the linac operational and diagnostic capabilities that enabled self-amplified spontaneous emission (SASE) operation of the FEL at 530 nm. Electron beam measurement techniques and recent results will be discussed. Beam properties are measured under the same operational conditions as those used for FEL studies. The nominal FEL beam parameters are as follows: 217 MeV beam energy; less than 0.15 mm-mrad normalized emittance; 100 A peak current from a 0.7-nC charge at a 7-psec bunch. |
| title: | High-Brightness Beams from a Light Source Injector: The Advanced Photon Source Low-Energy Undulator Test Line Linac |
| conference: | 2000 Linear Accelerator Conference |
| year: | 2000 |
| authors: | G. Travish,S. Biedron,M. Borland,M. Hahne,K. Harkay,J. Lewellen,A. Lumpkin,S. Milton,N. Sereno |
| abstract: | The use of existing linacs, and in particular light source injectors, for free-electron laser (FEL) experiments is becoming more common due to the desire to test FELs at ever shorter wavelengths. The high-brightness, highcurrent beams required by high gain FELs impose technical specifications that most existing linacs were not designed to meet. Moreover, the need for specialized diagnostics, especially shot-to-shot data acquisition, demands substantial modification and upgrade of conventional linacs. Improvements have been made to the Advanced Photon Source (APS) injector linac in order to produce and characterize high brightness beams. Specifically, effort has been directed at generating beams suitable for use in the low-energy undulator test line (LEUTL) FEL in support of fourth-generation light source research. The enhancements to the linac technical and diagnostic capabilities that allowed for self-amplified spontaneous emission (SASE) operation of the FEL at 530 nm are described. Recent results, including details on technical systems improvements and electron beam measurement techniques, will be discussed. The linac is capable of accelerating beams to over 650 MeV. The nominal FEL beam parameters used are as follows: 217 MeV energy; 0.1-0.2% rms energy spread; 4-8 um normalized rms emittance; 80-120 A peak current from a 0.2-0.7 nC charge at a 2-7 ps FWHM bunch. |
| title: | High-energy inverse free-electron laser accelerator |
| conference: | 3rd U.S. Summer School on High Energy Particle Accelerators |
| year: | 1985 |
| authors: | E. Courant,C. Pellegrini,W. Zakowicz |
| abstract: | The authors study the inverse free electron laser (IFEL) accelerator and show that it can accelerate electrons to the few hundred GeV region with average acceleration rates of the order of 200 MeV/m. Several possible accelerating structures are analysed, and the effect of synchrotron radiation losses is studied. The longitudinal phase stability of accelerated particles is also analysed. A Hamiltonian description, which takes into account the dissipative features of the IFEL accelerator, is introduced to study perturbations from the resonant acceleration. Adiabatic invariants are obtained and used to estimate the change of the electron phase space density during acceleration process. (22 References). |
| title: | High-energy inverse free-electron-laser accelerator |
| journal: | Physical Review A |
| vol-pages: | 2813-23 |
| year: | 1985 |
| authors: | E. Courant,C. Pellegrini,W. Zakowicz |
| abstract: | The authors study the inverse free-electron-laser (IFEL) accelerator and show that it can accelerate electrons to the few hundred GeV region with average acceleration rates of the order of 200 MeV/m. Several possible accelerating structures are analyzed, and the effect of synchrotron-radiation losses is studied. The longitudinal phase stability of accelerated particles is also analyzed. A Hamiltonian description, which takes into account the dissipative features of the IFEL accelerator, is introduced to study perturbations from the resonant acceleration. Adiabatic invariants are obtained and used to estimate the change of the electron phase-space density during the acceleration process. (22 References). |
| title: | High-gain free electron lasers as generators of short wavelength coherent radiation |
| conference: | Conference on Short Wavelength Coherent Radiation: Generation and Applications |
| year: | 1986 |
| authors: | K. Kim,C. Pellegrini |
| abstract: | The development of coherent radiation in high-gain free electron lasers, either from initial noise or from low-power input radiation, is analyzed in terms of three-dimensional Maxwell-Klimontovich equations. Exponential growth and saturation, transverse radiation profiles, transverse coherence and spectral features are discussed. Two possible systems of high-gain free electron lasers, one based on a storage ring and by-pass, another based on a linac and damping ring, are considered for the generation of 400 AA radiation. (19 References). |
| title: | Higher harmonic inverse free-electron laser interaction |
| journal: | Physical Review E |
| vol-pages: | |
| year: | 2005 |
| authors: | P. Musumeci,C. Pellegrini,J. Rosenzweig |
| abstract: | We expand the theory of the inverse free electron laser IFEL interaction to include the possibility of energy exchange that takes place when relativistic particles traversing an undulator interact with an electromagnetic wave of a frequency that is a harmonic of the fundamental wiggler resonant frequency. We derive the coupling coefficients as a function of the IFEL parameters for all harmonics, both odd and even. The theory is supported by simulation results obtained with a three-dimensional Lorentz equation solver code. Comparisons are made between the results of theory and simulations, and the recent UCLA IFEL experimental results where higher harmonic IFEL interaction was observed. |
| title: | Highlights of AAC 2000 Workshop |
| conference: | 2000 Linear Accelerator Conference |
| year: | 2000 |
| authors: | J. Rosenzweig |
| abstract: | The Advanced Accelerator Concepts 2000 (AAC2K) Workshop was held in Santa Fe in June, 2000, and included a wide array of conceptual and theoretical advances at the frontier of accelerator physics. This paper reviews the highlights of the workshop, with subjects ranging from acceleration using lasers, plasmas and microstructures, to the beam physics of muon colliders. Particular emphasis is given to the topics which are relevant to research at existing linear accelerator facilities, and the effect of this research on the capabilities of such facilities. |
| title: | Horizontal Phase-Space Distortions Arising from Magnetic Pulse Compression of an Intense, Relativistic Electron Beam |
| journal: | Physical Review Letters |
| vol-pages: | 074803 |
| year: | 2003 |
| authors: | S. Anderson,J. Rosenzweig,P. Musumeci,M. Thompson |
| abstract: | We report detailed measurements of the transverse phase space distortions induced by magnetic chicane compression of a high brightness, relativistic electron beam to subpicosecond length. A strong bifurcation in the phase space is observed when the beam is strongly compressed. This effect is analyzed using several computational models and is correlated to the folding of longitudinal phase space. The impact of these results on current research in collective beam effects in bending systems and implications for future short wavelength free-electron lasers and linear colliders are discussed. |
| title: | IFEL experiment at Neptune Lab |
| conference: | 2000 European Particle Accelerator Conference |
| year: | 2000 |
| authors: | P. Musumeci,C. Pellegrini |
| abstract: | We present a two stage Inverse Free Electron Laser accelerator proposed for construction at the UCLA Neptune Lab. Proof-of-principle experiments on the IFEL scheme have been carried out successfully. This experiment is intended to achieve a 100 MeV energy gain, staging two IFEL modules. It will use a 16 MeV electron beam, a 1 TW CO2 laser and two different tapered helical undulators. The problem of refocusing both laser and electron beam is analysed in detail. A preliminary beam-line layout and numerical simulations are presented. |
| title: | IFEL experiment at the Neptune Lab |
| conference: | 9th Advanced Accelerator Concepts Workshop |
| year published: | 2001 |
| year authored: | 2000 |
| authors: | P. Musumeci,C. Pellegrini |
| abstract: | We present a two stage Inverse Free Electron Laser accelerator proposed for construction at the UCLA Neptune Lab. Proof-of-principle experiments on the IFEL scheme have been carried out successfully. This experiment is intended to achieve a 100 MeV energy gain, staging two IFEL modules. It will use a 16 MeV electron beam, a 1 TW CO/sub 2/ laser and two different tapered helical undulators. The problem of refocusing both laser and electron beam is analyzed in detail. A preliminary beam-line layout and numerical simulation are presented. (11 References). |
| title: | Influence of electron beam halos on the FEL performance |
| conference: | 20th International Free Electron Laser Conference |
| year published: | 1999 |
| year authored: | 1998 |
| authors: | B. Faatz,S. Reiche |
| abstract: | For single-pass free-electron lasers (FEL), such as amplifiers and SASE devices, saturation of the radiation power has to be reached within the length of the undulator. Therefore, detailed knowledge of electron beam parameters is crucial. So far, simulations have been performed with a given rms emittance and energy spread. At short radiation wavelengths, hunch compressors are used to compress the electron beam to achieve the desired high peak currents. In addition, external focusing along the entire undulator is used to maintain a constant small radius. The rotation of phase space due to compression might lead to a significant part of the bunch in tails that could increase the gain length. Furthermore, it is in general not possible to match both the beam core and the tail to the focusing structure. In this contribution, the influence of these tails, both transverse and in energy, on the FEL performance will be investigated. Simulations will be performed for beam parameters that have been assumed for the TESLA Test Facility FEL at DESY. |
| title: | Initial commissioning results of the Next Generation Photoinjector |
| conference: | 7th Advanced Accelerator Concepts Workshop |
| year published: | 1997 |
| year authored: | 1996 |
| authors: | D. Palmer,X. Wang,R. Miller,M. Babzien,I. Ben-Zvi,C. Pellegrini,J. Sheehan,J. Skaritka,H. Winick,M. Woodle,V. Yakimenko |
| abstract: | The BNL/SLAC/UCLA symmetrized 1.6 Cell S-band emittance-compensated photoinjector has been installed at the Brookhaven Accelerator Test Facility (ATF). The commissioning results and performance of the photocathode injector are presented. This emittance-compensated photoinjector consists of the symmetrized BNL/SLAC/UCLA 1.6 cell S-band photocathode radio-frequency (RF) gun and a single solenoidal magnet for transverse emittance compensation. The highest acceleration field achieved on the cathode is 150 MV/m, and the normal operating field is 130 MV/m. The quantum efficiency of the copper cathode was measured to be 4.5*10/sup -5/. The transverse emittance and bunch length of the photoelectron beam were measured. The optimized RMS normalized emittance for a charge of 300 pC is 0.7 pi mm-mrad. The bunch length dependency of photoelectron beam on the RF gun phase and acceleration fields were experimentally investigated. (11 References). |
| title: | Initial gain measurements of an 800 nm SASE FEL, VISA |
| conference: | 22nd International Free Electron Laser Conference |
| year published: | 2001 |
| year authored: | 2000 |
| authors: | P. Frigola,A. Murokh,P. Musumeci,C. Pellegrini,S. Reiche,J. Rosenzweig,A. Tremaine,M. Babzien,I. Ben-Zvi,E. Johnson,R. Malone,G. Rakowsky,J. Skaritka,X. Wang,K. Van Bibber,L. Bertolini,J. Hill,G. Le Sage,M. Libkind,A. Toor,R. Carr,M. Cornacchia,L. Klaisner,H. Nuhn,R. Ruland,D. Nguyen |
| abstract: | The visible to infrared SASE amplifier (VISA) FEL is designed to obtain high gain at a radiation wavelength of 800 nm. The FEL uses the high brightness electron beam of the accelerator test facility (ATF), with energy of 72 MeV. VISA uses a novel, 4 m long, strong focusing undulator with a gap of 6 mm and a period of 1.8 cm. To obtain large gain the beam and undulator axis have to be aligned to better than 5 mu m. Results from initial measurements on the alignment, gain, and spectrum will be presented and compared to theoretical calculations and simulations. (10 References). |
| title: | Initial measurements of the UCLA RF photoinjector |
| conference: | Conference on High Intensity Electron Sources |
| year published: | 1994 |
| year authored: | 1993 |
| authors: | S. Hartman,N. Barov,C. Pellegrini,S. Park,J. Rosenzweig,G. Travish,R. Zhang,C. Clayton,P. Davis,M. Everett,C. Joshi,G. Hairapetian,S. Hartman,M. Hogan |
| abstract: | The 1.5 cell standing wave RF photoinjector has been operated for the past several months using a copper cathode. The photoinjector drive laser produces sub 2 ps pulses of UV ( lambda =256 nm) light with up to 200 mu J/pulse which generates up to 3 nC of charge, The emittance of the photoinjector was measured as a function of charge, RF launching phase, and peak accelerating field. Also, the quantum efficiency and pulse lengths of the laser beam and the electron beam were measured. (15 References). |
| title: | Initial measurements of the UCLA RF photoinjector |
| conference: | 15th International Free Electron Laser Conference |
| year published: | 1994 |
| year authored: | 1993 |
| authors: | S. Hartman,M. Hogan |
| abstract: | An RF photocathode gun which, along with a compact linac, forms the injection system for a planned 10 mm free-electron laser amplifier experiment, has been commissioned in the Particle Beam Physics Laboratory at UCLA. This high-gradient gun, based on the Brookhaven design, has emitted several picosecond, [right angle bracket]100 A electron beams of up to 4 MeV in energy. These beams have been characterized by a variety of diagnostics. The quantum efficiency of the copper cathode used has been measured at normal incidence, and at 70 degrees incidence, where the polarization dependence was also examined. Limits on laser intensity due to surface damage, and to longitudinal space charge suppression of photoemission have been explored. The energy and energy spread of the beam were characterized using a dipole spectrometer, while the time structure was examined using a picosecond resolution streak camera. Both energy spread and pulse length were found to be adversely affected by longitundinal space charge forces. The emittance of the beam was measured using the pepper pot Technique, and its dependence on space charge and rf phase were found. The impact of these results on imporving the design and operation of high brightness photoinjectors is discussed, in particular with respect to SASE FEL amplifiers such as the UCLA 10mm FEL, and the proposed SLAC X-ray FEL. |
| title: | Initial operation and beam characteristics of the UCLA S-band RF photo-injector |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | C. Pellegrini,N. Barov,S. Hartman,S. Park,J. Rosenzweig,G. Travish,R. Zhang,P. Davis,C. Joshi,G. Hairapetian |
| abstract: | The UCLA RF photo-injector system has been commissioned. All of the sub-components such as the high power RF, pico-second laser, RF photo-injector cavity, diagnostics, and supporting hardware have been tested and are operational. We briefly discuss the performance of the various components since the details of each subsystem are very lengthy. The laser delivers a sub 4 ps pulse containing 0-300 mu J of energy per pulse. The photo-injector produces 0-3 nC per bunch with an RF induced emittance of 1.5 pi (mm-mrad). (5 References). |
| title: | Initial operation of S-band plane wave transformer photoinjector |
| conference: | APS April Meeting |
| year: | 2000 |
| authors: | X. Ding,C. Pellegrini,J. Rosenzweig,S. Telfer |
| abstract: | An integrated S-Band RF photoinjector based on the plane wave transformer (PWT) is being built and operated in the Particle Beam Physics Laboratory at UCLA. This novel structure integrates a photocathode directly into a PWT Linac making the structure simple and compact. Due to the strong coupling between each adjacent cell, this structure is relatively easy to fabricate and operate. This photoinjector can provide high brightness beams at energies of 15 to 20MeV, with emittance less than 1mm-mrad at charge of 1 nC. These short-pulse beams can be used in various applications: space charge dominated beam physics studies, plasma lenses, plasma accelerators, free-electron laser microbunching techniques, and SASE-FEL physics studies. It will also provide commercial opportunities in chemistry, biology and medicine. The initial operation of the PWT photoinjector with high RF power is described. A comparation of experimental result and theoretical design is also discussed. |
| title: | Initial operation of the UCLA plane wave transformer (PWT) linac |
| conference: | 1995 Particle Accelerator Conference |
| year: | 1995 |
| authors: | R. Zhang,P. Davis,G. Hairapetian,M. Hogan,C. Joshi,M. Lampel,S. Park,C. Pellegrini,J. Rosenzweig,G. Travish |
| abstract: | We report on the initial operation of a novel compact rf linac-the plane wave transformer (PWT). The PWT is a 42 cm long, 8 cell standing-wave structure, operated at S-band, in a pi -mode. We present the properties of this linac at rf power levels from 4 MW to 8 MW and beam energy from 7 MeV to 10 MeV, measured initially using both dark current and photo-electrons. Some technical issues associated with the operation are discussed. Future improvements of the PWT, using a modified design, are also studied. (6 References). |
| title: | Injection and dynamics of accelerated beams |
| conference: | ICFA Second Generation Plasma Acceleration Workshop |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | J. Rosenzweig |
| abstract: | This paper is a summary of the discussions undertaken by the working group on injection and accelerated beam dynamics at the 1st ICFA novel and advanced accelerator workshop on second generation plasma accelerators. The second generation of work on plasma accelerators is aimed to bring the accelerated beams up to the quality needed for applications such as high-energy physics linear colliders. To begin, first generation, or proof-of-principle, experiments and concepts were reviewed. To map the work needed in the second generation of development, the demands of the applications were examined, and an improved framework for discussing the viability of plasma accelerators was constructed. In particular, the issues scaling applications to the short wavelengths characteristic of plasma accelerators was discussed, as was the appropriate characterization of the beam quality in these devices, and the connection between plasma accelerator and conventional accelerator design. Within this framework, the working group discussed electron sources and injectors, the effects of drive beam evolution on accelerated beam dynamics, this effects of nonlinear plasma wave fields on beam phase space, stochastic processes, spatial and temporal beam-plasma wave matching, and future second-generation experimental goals and techniques. |
| title: | Instability of compensated beam-beam collisions |
| conference: | 1989 Workshop on Advanced Accelerator Concepts |
| year: | 1989 |
| authors: | J. Rosenzweig,B. Autin |
| abstract: | The beam-beam disruption phenomena in linear colliders are increasingly seen as a source of serious problems for these machines. The maximum disruption-induced angle introduces a constraint on final focusing system apertures, which has led to the complication of interaction point crossing angles. Additional constraints arise due to the desire to minimize the energy spread due to beamstrahlung energy loss to acceptable levels. Much more seriously, the beamstrahlung photons produced during disruption have been shown to pair-produce via interaction with the opposing bunch's disruption fields. (11 References). |
| title: | Intra-undulator measurements at VISA FEL |
| conference: | 22nd International Free Electron Laser Conference |
| year published: | 2001 |
| year authored: | 2000 |
| authors: | A. Murokh,P. Frigola,C. Pellegrini,J. Rosenzweig,A. Tremaine,E. Johnson,X. Wang,V. Yakimenko,L. Klaisner,H. Nuhn,A. Toor |
| abstract: | We describe a diagnostics system developed, to measure exponential gain properties and the electron beam dynamics inside the strong focusing 4-m long undulator for the VISA (Visible to Infrared SASE Amplifier) FEL. The technical challenges included working inside the small undulator gap, optimising the electron beam diagnostics in the high background environment of the spontaneous undulator radiation, multiplexing and transporting the photon beam. Initial results are discussed. |
| title: | Introduction to the physics of the free electron laser |
| conference: | Joint US-CERN School of Particle Accelerators: Frontiers of Particle Beams |
| year published: | 1988 |
| year authored: | 1986 |
| authors: | J. Murphy,C. Pellegrini |
| abstract: | The authors explore the basic physics of the FEL, emphasizing the underlying physical principles with a minimum of mathematics. The description is based on the classical theory of the FEL as that is sufficient to explain most of the physics. The elementary principles of operation of an FEL and the trajectory of an electron in the magnetic field of both helical and planar undulator magnets are presented. The trajectories are then used to calculate the spontaneous emission of an electron in an undulator magnet. The electron equations of motion are extended to include the forces due to both the undulator and the radiation field. If the change in the radiation field is small in one pass through the undulator, one can compute the so-called 'small signal gain' of the FEL using only the particle equations of motion; the radiation field is assumed to remain constant. The potential for increasing the efficiency of an FEL by tapering the period and magnetic field strength of the undulator magnet is discussed. |
| title: | Inverse Free Electron Laser Experiment at the Neptune Laboratory |
| conference: | 10th Advanced Accelerator Concepts Workshop |
| year: | 2002 |
| authors: | P. Musumeci,C. Pellegrini,J. Rosenzweig,A. Varfolomeev,S. Tolmachev,T. Yarovoi |
| abstract: | We present an Inverse Free Electron Laser accelerator proposed for construction at the UCLA Neptune Laboratory. This experiment will use a 1 TW CO2 laser to accelerate through two strongly tapered undulators an electron beam from 16 MeV up to 5 MeV. The scheme proposed is the diffraction dominated IFEL interaction. The Raleigh range of the laser beam is about 2 cm, much shorter than the interaction length (the undulator length is 50 cm). In this regime adiabatic capture is possible in the first part of the undulator. In the focus region, we propose a solution to the problem of the dephasing between electrons and photons due to the |
| title: | Investigations of electron-beam microbunching and beam coalignment using CTR in a high-gain SASE FEL |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | A. Lumpkin,W. Berg,S. Biedron,M. Borland,Y. Chae,R. Dejus,J. Lewellen,S. Milton,E. Moog,G. Travish,B. Yang |
| abstract: | We recently extended our experiments on z-dependent electron-beam microbunching using coherent transition radiation (CTR) into the high-gain, self-amplified spontaneous emission free-electron laser (FEL) regime. The UV-visible FEL at the Advanced Photon Source was operated at 530 nm and 385 nm using the bunch-compressed photocathode gun electron beam, linac, and 21.6 m of undulator length. The longitudinal microbunching of the electron beam was tracked by inserting a metal foil and a mirror after each of the nine 2.4-m-long undulators. The visible CTR generated by the electron-beam interaction was imaged and analyzed for z-dependent intensity, angular distribution, and spot size. Additionally, the image centroids and structures were used in evaluating the critical electron beam/photon beam overlap issue as a complement to the trajectory data from the beam position monitors. (9 References). |
| title: | Ion clearing by cyclotron resonance shaking |
| conference: | 1991 Particle Accelerator Conference |
| year: | 1991 |
| authors: | P. Zhou,J. Rosenzweig |
| abstract: | A new concept in ion clearing for storage rings, that of resonant removal of ions in dipoles by shaking the beam horizontally near the ion cyclotron frequency is discussed. This method of beam shaking is similar to the variations on ion bounce shaking but has advantages in requiring a narrower bandwidth of shaking frequencies and in much higher achievable ion kinetic energies. The results of analytical theory, and computer simulations are discussed. (7 References). |
| title: | Is the X-ray FEL the 4th generation light source? |
| conference: | 1998 European Particle Accelerator Conference |
| year: | 1998 |
| authors: | C. Pellegrini |
| abstract: | Recent theoretical and experimental work has led to important advances in the physics of Self-Amplified Spontaneous Emission free-electron-lasers (SASE-FELs), and in the production of high brightness, high energy electron beams. This work has made possible the design and construction of X-ray FELs at a few to 0.1 nm. The X-ray FEL has the characteristics required for a ''4th Generation Light Source'': diffraction limited radiation, subpicosecond pulse length, peak and average brightness largely exceeding that of 3rd generation sources. We review the status of SASE-FELs, and of the X-ray FEL projects. |
| title: | Isochronous storage rings and high luminosity electron-positron colliders |
| conference: | Conference on Beam Dynamics Issues of High-Luminosity Asymmetric Collider Rings |
| year: | 1990 |
| authors: | C. Pellegrini,D. Robin |
| abstract: | The interest in studying CP and possibly CPT violations in B and phi meson decay has lead recently to several proposals for the construction of B and phi factories. With a conventional storage ring collider, high luminosity 10 to 100 times larger than maximum obtained up to now, is obtained by increasing the stored electron and positron beam currents from the 10-100 mA range to the several Ampere level. This very large beam current raises questions of collective instabilities and vacuum and RF system design. In addition the RF power needed to compensate the synchrotron radiation losses is of the order of 5 to 10 MW. The authors study the possibility of obtaining this high luminosity keeping the beam current at the 100 mA level, by using an 'isochronous ring' and reducing the bunch length and the beta function at the interaction point. (7 References). |
| title: | Isochronous storage-rings and high-luminosity electron-positron colliders |
| journal: | Annals of the NY Academy of Sciences |
| vol-pages: | 163-71 |
| year: | 1991 |
| authors: | C. Pellegrini,D. Robin |
| abstract: |
| title: | LIMITS ON PRODUCTION OF NARROW BAND PHOTONS FROM INVERSE COMPTON SCATTERING |
| conference: | |
| year published: | 2006 |
| year authored: | 2005 |
| authors: | J.B ROSENZWEIG,A.M COOK,M. DUNNING,R.J ENGLAND,P. MUSUMECI,M. BELLAVEGLIA,M. BOSCOLO,L. CATANI,A. CIANCHI,G. PIRRO,M. FERRARIO,D. FILLIPETTO,G. GATTI,L. PALUMBO,L. SERAFINI,C. VICARIO,S. JONES |
| abstract: | In using the inverse Compton scattering (ICS) interaction as a high brilliance, short wavelength radiation source, one collides two beams, one an intense laser, and the other a high charge, short pulse electron beam. In order to maximize the flux of photons from ICS, one must focus both beams strongly, which implies both use of short beams and the existence of large angles in the interaction. One aspect of brilliance is the narrowness of the wavelength band emitted by the source. This paper explores the limits of ICS-based source brilliance based on inherent wavelength broadening effects that arise due to focal angles, laser energy density, and finite laser pulse length effects. It is shown that for a nominal 1% desired bandwidth, that one obtains approximately one scattered photon per electron in a head-on collision geometry. |
| title: | LabVIEW Virtual Instruments Instruction Manual, Version 1.0 |
| format: | unpublished |
| year: | 1991 |
| authors: | . |
| abstract: | This document describes a set of LabVIEW Virtual Instruments (VI's) for use in the Saturnus lab. The purpose of the software library is to allow users to easily make "programs" for the CAMAC modules in our lab. The library contains all the low level controls needed to interface to the CAMAC crate. The task of controlling the modules is thus reduced to an almost trivial level. This manual describes the library. Fundamentals of CAMAC programming are also mentioned. It is assumed that the reader has a basic working knowledge of LabVIEW. |
| title: | Laminar flow in non-relativistic intense proton beams |
| conference: | 1998 European Particle Accelerator Conference |
| year: | 1998 |
| authors: | L. Serafini,J. Rosenzweig |
| abstract: | An approach to the envelope description of laminar non-relativistic particle beams is presented, which describes a new kind of equilibrium flow for strongly space charge dominated proton beams subject to acceleration in RF Linacs. The analysis is based on the extension of the invariant envelope concept, recently introduced in the field of RF photo-injectors[1], to nonrelativistic particle beams whose envelope is dominated by coherent plasma oscillations instead of incoherent betatron motion associated to thermal rms emittance. An exact analytical solution of the rms envelope equation is presented, describing both the laminar regime and the transition to the thermal regime: the impact of this new beam equilibrium on the design of high intensity Linacs is discussed. |
| title: | Large-field-strength short-period undulator design |
| conference: | 13th International Free Electron Laser Conference |
| year published: | 1992 |
| year authored: | 1991 |
| authors: | A. Varfolomeev,S. Ivanchenkov,A. Khlebnikov,C. Pellegrini,G. Baranov,V. Michailov |
| abstract: | A high-quality strong-field hybrid undulator has been designed for an infrared FEL project to be performed at UCLA. The primary magnetic flux is provided by C-shaped vanadium-permendur yokes and SmCo_5 magnets. An additional magnetic flux is supplied by thin NdFeB magnet blocks placed between the yoke poles. This magnet geometry provides a high saturation limit for the magnetic field in the gap area. With the 15 mm period and 5 mm gap a peak on-axis field of 7.3 kG has been achieved. The undulator contains 40 periods. The high accuracy of the yoke poles alignment along with the ability to move the thin permanent magnet blocks provides an on-axis magnetic field accuracy better than 0.5%. (9 References). |
| title: | Limitations on Measuring a Transverse Profile of Ultradense Electron Beams with Scintillators |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | A. Murokh,J. Rosenzweig,I. Ben-Zvi,X. Wang,V. Yakimenko |
| abstract: | As the high-brightness electron beams become denser and reach sub-100 um sizes, a resolution of the transverse profile diagnostics become an important issue. The applicability of the traditional scintillators as the diagnostics for most generic transverse properties of small dense beams is questionable. Recently, a YAG:Ce single crystal was used successfully, but studies indicated the presence of saturation effects. At BNL-ATF (Accelerator Test Facility) we have generated ultra-small beams, and continued an experimental work to further illuminate the nature of YAG:Ce saturation. We have also evaluated alternative diagnostics, such as LuAG:Ce. Imaging properties of various diagnostics were studied, including measurements of emission spectra. |
| title: | Limitations on the resolution of YAG:Ce beam profile monitor for high brightness electron beam |
| conference: | 2nd ICFA Advanced Accelerator Workshop on the Physics of High Brightness Beams |
| year published: | 2000 |
| year authored: | 1999 |
| authors: | A. Murokh,J. Rosenzweig,V. Yakimenko,E. Johnson,X. Wang |
| abstract: | The performance of single crystal YAG:Ce (Y_(3)Al_(5)O_(12)) beam profile monitors was studied for transverse masurements on the high brightness ultrarelativistic electron beam at Accelerator Test Facility (ATF) at BNL. The test demonstrated systematic intensity dependent beam enlargement on YAG monitors, compared to other diagnostics. Possible mechanisms of the effect have been studied. The quantitative examination was performed and compared to the developed phenomenological models. Limitations on the use of YAG:Ce diagnostics are discussed with respect to the high-brightness electron sources. |
| title: | Limits on production of narrow band photons from inverse Compton scattering |
| conference: | |
| year: | 2006 |
| authors: | J. Rosenzweig,O. Williams |
| abstract: | In using the inverse Compton scattering (ICS) interaction as a high brilliance, short wavelength radiation source, one collides two beams, one an intense laser, and the other a high charge, short pulse electron beam. In order to maximize the flux of photons from ICS, one must focus both beams strongly, which implies both use of short beams and the existence of large angles in the interaction. One aspect of brilliance is the narrowness of the wavelength band emitted by the source. This paper explores the limits of ICS-based source brilliance based on inherent wavelength broadening effects that arise due to focal angles, laser energy density, and finite laser pulse length effects. It is shown that for a nominal 1% desired bandwidth, that one obtains approximately one scattered photon per electron in a head-on collision geometry |
| title: | Longitudinal Beam-Beam Effects in Circular Colliders |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| authors: | M. Hogan,J. Rosenzweig |
| abstract: | The longitudinal beam-beam interaction, which can lead to incoherent heating, synchrobctatron coupling, and coherent longitudinal instabilities in circular colliders, is examined. This analysis discusses two types of energy kicks, those due to the transverse particle motion coupling to the electric portion of the transverse kick, and those derived from the inductive electric field induced near the interaction, which is obtained from the transverse kick through use of a generalization of the Panofsky-Wenzel Theorem. Implications for low energy e+e- colliders (phi & B factories) with beams crossing head-on, and at finite angles, with and without crab crossing, are discussed. |
| title: | Longitudinal instabilities in circular accelerator and storage rings |
| conference: | 1981 Particle Accelerator Conference |
| year: | 1981 |
| authors: | C. Pellegrini |
| abstract: | Coherent instabilities of particle beams in circular accelerators and storage rings have been the subject of many theoretical and experimental works. The coherent instabilities discussed are produced by the electromagnetic interaction of the charged particle beam with the walls of the vacuum chamber in which the beam is moving. The author reviews the general problem of the longitudinal stability of bunched beams. Although there is no general solution it is possible to identify regions in the frequency-risetime space where one can obtain approximate solutions. An expression for the collective oscillation frequency is presented and expressions for the effective coupling impedance are given for the high or low frequency and slow and fast blow-up regimes. (14 References). |
| title: | Luminosity enhancement in linear colliders using a short focal length plasma lens |
| conference: | UCLA Workshop on Linear-Collider BB Factory Conceptual Design |
| year: | 1987 |
| authors: | J. Rosenzweig,B. Cole,D. Larson,D. Cline |
| abstract: | It is likely that powerful new focusing methods will be required for the linear colliders of the future. One scheme that shows much promise is plasma focusing in which a particle bunch traversing a plasma is focused by its own wake-fields. The authors present a review of the theory of self pinching due to plasma wake-fields and extend these previous results by discussing how this effect might be of use in constructing a short focal length plasma lens. They then discuss the general properties of short focal length lenses, and the luminosity enhancement that can be theoretically obtained from them. They also examine some of the practical issues involved in installing a plasma lens in a linear collider. (12 References). |
| title: | MAFIA Studies of the Plane Wave Tranformer Linac |
| format: | unpublished |
| year published: | Januray 6, 1992 |
| year authored: | 1992 |
| authors: | S. Hartman |
| abstract: | In designing a high power rf-accelerator one needs to examine any filed disturbances created by asymmetries in teh structure. In the following we present a study of the disturbance of the modes using the three-dimensional frequency domain solver MAFIA[1]. We pay particular attention to perturbations in the accelerating mode and also to higher order modes which can be excited by the electron beam itself. These perturbations in the accelerating mode and off axis kicks due to the higher order modes give rise to emittance growth. Some ideas of how to redesign the support structure in order to iminimze accelerating mode perturbation effects and also of how to damp out unwanted higher order modes are discussed. |
| title: | Measured free-electron laser microbunching using coherent transition radiation |
| conference: | 20th International Free Electron Laser Conference |
| year published: | 1999 |
| year authored: | 1998 |
| authors: | A. Tremaine,J. Rosenzweig,S. Anderson,P. Frigola,M. Hogan,A. Murokh,C. Pellegrini,D. Nguyen,R. Sheffield |
| abstract: | The microbunch distribution of an electron beam exiting a SASE free-electron laser has been measured using the emitted coherent transition radiation (CTR) produced from a thin aluminum foil placed at the end of the undulator. The wavelength of the coherent transition radiation is shown to be the same as the FEL wavelength, and thus a measure of the beam microbunch spacing. Also, the study of the CTR linewidth and angular acceptance of the radiation captured are shown to be derived from this coherent radiative process. Scattering effects on the forward emitted transition radiation from the electron beam traversing an aluminum foil are also considered. (11 References). |
| title: | Measurement of the Dipole Magnets |
| format: | unpublished |
| year: | 1993 |
| authors: | N. Barov,P. Tran,S. Thompson,B. Gitter |
| abstract: | The four Saturnus dipole magnets were calibrated with a Hall probe using a machinist's rotary table and a stepping motor to vary position. The setup was controlled by a Macintosh LC computer using LabView software. The field vs. current relationship was also measured. Single particle motion through the magnet was simulated, making a comparison of the real magnet to an ideal one. |
| title: | Measurement of the variation of machine parameters and the effect of the power supplies ripple on the instantaneous tunes at SPEAR |
| conference: | 1997 Particle Accelerator Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | A. Terebilo,C. Pellegrini,M. Cornacchia,J. Corbett,D. Martin |
| abstract: | For long term stability analysis, time variation of tunes is important. We have proposed and tested a technique for measuring the magnitude of this variation. This was made possible by using tune extraction algorithms that require small number of turns thus giving an instantaneous tune of the machine. In this paper we demonstrate the measured effect of the tune modulation with 60 Hz power supplies ripple, power line interference from the SLAC linac operating at 30 Hz repetition rate, and non-periodic variation. (8 References). |
| title: | Measurements of High Gain and Intensity Fluctuations in a Self-Amplified, Spontaneous-Emission Free-Electron Laser |
| journal: | Physical Review Letters |
| vol-pages: | 289-92 |
| year: | 1998 |
| authors: | M. Hogan,C. Pellegrini,J. Rosenzweig,G. Travish,A. Varfolomeev,S. Anderson,K. Bishofberger,P. Frigola,A. Murokh,N. Osmanov,S. Reiche,A. Tremaine |
| abstract: | We report measurements of large gain for a single pass free-electron laser operating in self-amplified spontaneous emission (SASE) at 16 mm starting from noise. We also report the first observation and analysis of intensity fluctuations of the SASE radiation intensity in the high gain regime. The results are compared with theoretical predictions and simulations. |
| title: | Measurements of gain larger than 10(5) at 12 mu m in a self-amplified spontaneous-emission free-electron laser |
| journal: | Physical Review Letters |
| vol-pages: | 4867-70 |
| year: | 1998 |
| authors: | M. Hogan,C. Pellegrini,J. Rosenzweig,S. Anderson,P. Frigola,A. Tremaine,C. Fortgang,D. Nguyen,R. Sheffield,J. Kinross-Wright,A. Varfolomeev,A. Varfolomeev,S. Tolmachev,R. Carr |
| abstract: | We report measurements of very large output intensities corresponding to a gain larger than 10/sup 5/ for a single pass free-electron laser operating in the self-amplified spontaneous emission (SASE) mode at 12 mu m. We also report the observation and analysis of intensity fluctuations of the SASE radiation intensity in the high-gain regime. The results are compared with theoretical predictions and simulations. (18 References). |
| title: | Measurements of high gain and noise fluctuations in a SASE free electron laser |
| conference: | Workshop on Single Pass, High Gain FELs Starting from Noise Aiming at Coherent X-Rays |
| year: | 1997 |
| authors: | M. Hogan,S. Anderson,K. Bishofberger,P. Frigola,A. Murokh,N. Osmanov,C. Pellegrini,S. Reiche,J. Rosenzweig,G. Travish,A. Tremaine,A. Varfolomeev |
| abstract: | We report measurements of large gain for a single pass Free Electron Laser operating in Self Amplified Spontaneous Emission (SASE) at 16 mu m starting from noise. We also report the first observation and analysis of intensity fluctuations of the SASE radiation intensity in the high gain regime. The results are compared with theoretical predictions and simulations. (11 References). |
| title: | Measurements of high gain and noise fluctuations in a SASE free electron laser |
| conference: | 1997 Particle Accelerator Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | . |
| abstract: | We report measurements of large gain for a single pass Free Electron Laser operating in Self Amplified Spontaneous Emission (SASE) at 16 mu m starting from noise. We also report the first observation and analysis of intensity fluctuations of the SASE radiation intensity in the high gain regime. The results are compared with theoretical predictions and simulations. (11 References). |
| title: | Measurements of high gain and noise fluctuations in a SASE free electron laser |
| conference: | 19th International Free Electron Laser Conference |
| year published: | 1998 |
| year authored: | 1997 |
| authors: | . |
| abstract: | We report measurements of large gain for a single pass free-electron laser operating in self-amplified spontaneous emission (SASE) at 16 mu m starting from noise. We also report the first observation and analysis of intensity fluctuations of the SASE radiation intensity in the high-gain regime. The results are compared with theoretical predictions and simulations. (11 References). |
| title: | Measurements of nonlinear harmonic radiation and harmonic microbunching in a visible SASE FEL |
| conference: | 24th International Free Electron Laser Conference |
| year published: | 2003 |
| year authored: | 2002 |
| authors: | A. Tremaine,X. Wang,M. Babzien,I. Ben-Zvi,M. Cornacchia,R. Malone,A. Murokh,H. Nuhn,C. Pellegrini,S. Reiche,J. Rosenzweig,J. Skaritka,V. Yakimenko |
| abstract: | The experimental characterization of nonlinear harmonic generation (NHG) and electron beam microbunching at saturation from a visible SASE FEL are presented in this report. The gain lengths, spectra and energies of NHG were experimentally measured up to the third harmonic, and agree with theoretical predictions. Electron beam microbunching in both the fundamental and the second harmonic as the function of the SASE output were experimentally observed over the full range of SASE gain. The bunching factors for both the fundamental (b(1)) and second harmonic (b(2)) were experimentally characterized at saturation. The microbunching data provides another test of SASE saturation as well as correlating the NHG and electron beam microbunching modes to the fundamental SASE. |
| title: | Measurements of plasma wake-fields in the blow-out regime |
| conference: | 1995 Particle Accelerator Conference |
| year: | 1995 |
| authors: | N. Barov,M. Conde,J. Rosenzweig,P. Schoessow,G. Cox,W. Gai,R. Konecny,J. Power,J. Simpson |
| abstract: | Initial results from nonlinear plasma wake-field experiments at the Argonne Wakefield Accelerator (AWA) test facility are reported. This nonlinear "blow-out" regime is characterized by the complete ejection of the plasma electrons from the beam channel. The wake-fields in this case are of notably high quality for acceleration of electrons, as the acceleration is independent of transverse position, and the focusing is linear and independent of longitudinal position within the electron depleted region, allowing self-consistent guiding of the majority of the driving electron beam. Initial measurements of the energy gain in a witness beam indicate a positive shift in its energy distribution of at least 0.5 MeV. (9 References). |
| title: | Measurements of the octupole-induced amplitude-dependent frequency shift in SPEAR |
| conference: | 1995 Particle Accelerator Conference |
| year: | 1995 |
| authors: | P. Tran,C. Pellegrini,J. Yang,M. Cornacchia,J. Corbett |
| abstract: | Four octupoles are used in SPEAR to provide the frequency spread for Landau damping of coupled-bunch motions at high current. With the planned implementation of a new low-emittance lattice, the effectiveness of the octupoles needs to be quantified. The recent development of a multi-dimensional turn-by-turn phase-space monitor and the availability of an accurate frequency analysis technique have made measurement of the octupole-induced amplitude-dependent frequency shift in the new SPEAR lattice possible. This paper presents the data collection and analysis procedures, and compares experimental results to model-based simulations. (5 References). |
| title: | Measurements of the tune variations induced by non-linearities in lepton machines |
| conference: | 1996 European Particle Accelerator Conference |
| year published: | 1997 |
| year authored: | 1996 |
| authors: | R. Bartolini,M. Giovannozzi,W. Scandale,A. Verdier,C. Pellegrini,P. Tran,E. Todesco,J. Corbett,M. Cornacchia |
| abstract: | The precise measurement of the betatron tune as a function of the oscillation amplitude provides a useful information on non-linear beam dynamics. In lepton accelerators, this measurement is made difficult due to various damping mechanism. To counteract this, we propose to use algorithms that provide a precise measurement of the tune in a small number of turns. We apply these procedures in LEP at injection and collision energy, as well as in SPEAR at injection energy. Collections of experimental data, and a first comparison with the results of model-based simulations are discussed. (9 References). |
| title: | Measuring FEL radiation properties at VISA-FEL |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | A. Murokh,R. Agustsson,P. Frigola,C. Pellegrini,S. Reiche,J. Rosenzweig,A. Tremaine,M. Babzien,I. Ben-Zvi,E. Johnson,R. Malone,G. Rakowsky,J. Skaritka,X. Wang,K. Van Bibber,L. Bertolini,J. Hill,G. Le Sage,M. Libkind,A. Toor,R. Carr,M. Cornacchia,L. Klaisner,H. Nuhn,R. Ruland |
| abstract: | The VISA (Visible to Infrared SASE Amplifier) SASE free electron laser has been successfully operated at the Accelerator Test Facility (ATF) at BNL. High gain and saturation were observed at 840 nm. We describe here the diagnostic system, experimental procedures and data reduction algorithms, as the FEL performance was measured along the length of the undulator. We also discuss selected spectral radiation measurements. (10 References). |
| title: | Memo: RF Power for the PWT LInac |
| format: | unpublished |
| year: | 1993 |
| authors: | R. Zhang |
| abstract: | The plane-wave transformer (PWT) linac, proposed by Swenson, will be used in the Saturnus, the UCLA high gain infrared FEL project. The FEL's output wavelength is designed to match the 10.6 um radiation which CO2 lasers produce.... |
| title: | Memo: Tentative Design of the Waveguide FEL at UCLA |
| format: | unpublished |
| year: | 1993 |
| authors: | R. Zhang |
| abstract: | In order to investigate the slippage effects in FELs, we are going to design a millimeter FEL with the following parameters: .... |
| title: | Microwave Systems for Photocathode Gun and RF Linac at UCLA |
| format: | |
| year published: | April 16, 1991 |
| year authored: | 1991 |
| authors: | S. Park |
| abstract: | This note describes the rf systems starting from the locked laser's crystal oscillator to 20MW of microwave output from the klystron. Details on high power waveguide components[1], modulator[2], and control diagnostics can be found elsewhere. The main emphasis will be on the frequency multiplier and preamplifier to the klystron. These two systems are to accomplish two objectives: (1) Synchronize, or phase lock, the operation of laser and rf systems; (2) Provide input signal for klystron with proper frequency and power. |
| title: | Mitigation of RF Gun Breakdown by Removal of Tuning Rods in High Field Regions |
| conference: | Erice 2005 |
| year authored: | 2005 |
| authors: | A.M Cook,J.B Rosenzweig,M. Dunning,P. Frigola,K. Serratto |
| abstract: | The pi-mode resonant frequency of the 1.6 cell SLAC/BNL/UCLA style RF photoinjector electron gun is conventionally tuned using cylindrical copper tuning pieces that extend into the full-cell cavity through holes in the side of the gun. This design begins to fail in many versions of this popular gun design at higher voltage levels, when the cavity undergoes electric breakdown in the vicinity of the tuners. In order to remove the tuners from the region of high electric field, mitigating this problem, one must change the full cell geometry significantly. We have investigated a method for accomplishing this, in which we stretch the gun structure to tune the resonant frequency up by over 2 MHz. We constructed a device to perform this stretching and tested the modified photoinjector in an RF test bed. We succeeded in putting approximately 8.4 MW of RF power into the gun, an improvement over the 4 MW routinely achieved with a similar gun using conventional tuning methods installed at the UCLA Neptune laboratory. Recent results in testing this gun with a magnesium cathode insert are reported as well. |
| title: | Modeling Photo-desorption in High Current Storage Rings |
| format: | unpublished |
| year: | 1991 |
| authors: | W. Barletta |
| abstract: | A phenomenological model of photo-desorption that includes effects of dose dependence and diffuse photon reflection allows one to compute the leveling of gas loads high current storage rings that typify heavy flavor factories. The model also permits one to estimate chamber commissioning times. |
| title: | Modeling of the X-ray Radiation Dependence on Power in High Gradient Radio-frequency Accelerator Structures |
| format: | unpublished |
| year published: | October 9, 1995 |
| year authored: | 1995 |
| authors: | D. Gooden,J. Rosenzweig |
| abstract: | It has long been known that field-emitted (FE) electron current is what generates the x-ray radiation from high-power RF accelerating strucutures, but it has not yet been qualitatively understood how the radiation varies with the microwave power input to these structures. This paper will show that from successive measurements of the RF power at a single position and the corresponding radiation dose rate ... |
| title: | Monitoring and Manipulation of Sub-picosecond Beams |
| format: | unpublished |
| year published: | May 30, 2002 |
| year authored: | 2002 |
| authors: | J. Rosenzweig |
| abstract: | Outline: Applications of sub-picosecond beams: a UCLA-centric view Sub-picosecond beam generation Sub-picosecond beam manipulation Sub-picosecond beam diagnosis The future |
| title: | Monitoring and manipulation of sub-picosecond beams |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| authors: | J. Rosenzweig |
| abstract: | In cutting-edge applications such as advanced accelerators and free-electron lasers, very high brightness beams of duration shorter than a picosecond are required. Further, these applications demand specific types of longitudinal beam profiles, such as pulse trains, and ramped pulses. The production of such types of beams present challenges both in technique, and in the instrumentation required to verify the method employed. The techniques for producing such short beams which have received the most investigation in recent years include chicane compression, and modulation via free-electron laser mechanism and its inverse. We discuss the principles and relevant single particle and collective effects which impact their performance. We review progress in implementing these schemes, as well as newer concepts such as relativistic velocity bunching and use of negative R_56 compressors. We also discussed the challenges in diagnosing these state-of-the-art beam systems. |
| title: | Multi-dimensional free-electron laser simulation codes: a comparison study |
| conference: | 21st International Free Electron Laser Conference |
| year published: | 2000 |
| year authored: | 1999 |
| authors: | S. Biedron,Y. Chae,R. Dejus,B. Faatz,H. Freund,S. Milton,H. Nuhn,S. Reiche |
| abstract: | A self-amplified spontaneous emission (SASE) free-electron laser(FEL) is under construction at the Advanced Photon Source (APS). Five FEL simulation codes were used in the design phase: GENESIS, GINGER, MEDUSA, RON, and TDA3D. Initial comparisons between each of these independent formulations show good agreement for the parameters of the APS SASE FEL. |
| title: | Multibunch Operation of the 1GeV Machine |
| format: | tech note |
| year: | 1988 |
| authors: | A. Sessler,G. Travish,S. Yu |
| abstract: |
| title: | Multiple-fluid models for plasma wake-field phenomena |
| journal: | Physical Review A |
| vol-pages: | 5249-55 |
| year: | 1989 |
| authors: | J. Rosenzweig |
| abstract: | In this paper the author presents various treatments of plasma wake-field phenomena which employ multiple-fluid models. These models generalize the one-dimensional, nonlinear, relativistic single-fluid model which has been used extensively in previous plasma wake-field calculations. Using a two-fluid model, the author discusses the interaction of a low-energy continuous electron beam with wake-field-generated plasma waves. The phenomena of continuous-beam modulation and wave period shortening are discussed. The relationship between these effects and the two-stream instability is also examined. Also, using a three-fluid model, effects due to plasma electron temperature in nonlinear plasma wake-fields are examined and compared to previous work. Finally, the consequences of ion motion induced by large-amplitude electron plasma waves are calculated by including the fluid behavior of the ions. (20 References). |
| title: | Neptune Second Harmonic Generation Autocorrelator |
| format: | tech note |
| year: | 2005 |
| authors: | R. England |
| abstract: | This document provides detailed information on the basic theoretical knowledge required to understand the operational principles of the Second Harmonic Generation Autocorrelator used for measuring the pulse length of the infrared drive laser at the Neptune Laboratory. This autocorrelator was originally assembled by Kari Sanders and Sergei Tochitsky ca. 2000-2001. Some information about its operation may be found in Kari Sanders' master's thesis. In short, the autocorrelator operates by splitting the infrared (1064nm) pulse produced by the Neptune regenerative amplifier and grating compressor and then crossing the two split pulses inside of a nonlinear KDP crystal, via a Type I "ooe" interaction, to produce noncollinear second harmonic frequency upconversion to green (532 nm). The intensity of the green as a function of the delay between the two split pulses produces the autocorrelation of the pulse, which can be used to extract the pulse length and (to some extent) the time structure of the pulse. The theory of autocorrelation will not be discussed in this document. |
| title: | New Features in UCLA-PARMELA v 2.1 |
| format: | tech note |
| year: | 2005 |
| authors: | R. England |
| abstract: | This document describes modifications to the UCLA-PARMELA source code version 2.0. The modifications were made by R. J. England during the period from 2003 to 2005. The changes to the code consist of: (1) the implementation of the "SEXT" card for sextupoles, and (2) changes to the "TRWAVE" card which permit the fields to be printed out to a data file. These changes are detailed in the following subsections. In addition, (3) I document the input structure for the CELL card in versions 2.0 and 2.1 since this was found to differ from the description given in the UCLA-PARMELA manual. The modified code version number has been increased to v 2.1. |
| title: | New Vacuum Chamber for the Plasma Density Transition-Trapping Experiment |
| format: | tech note |
| year: | 2003 |
| authors: | M. Schneider,M. Thompson |
| abstract: | The plasma density transition trapping experiment is designed to capture an electron beam and modify its quality (emittance, energy spread, and brightness) via a plasma wake-field [1]. The Particle Beam Physics Laboratory (PBPL) transition-trapping plasma experiment requires a chamber to support the confined plasma source, in-vacuum diagnostics and associated hardware. Initial measurements on the plasma source utilized a chamber initially created for an underdense plasma lens experiment [2]. However, current research and future positioning of the plasma source required drastic improvements of nearly all facets of the chamber design. The initial plan was to rearrange the plasma source to move the interaction box onto the opposite side of the pumping-Tee (see picture below). This proved successful to measure plasma densities at or above the required value to carry out the plasma transition-trapping experiment. However, because the original design of the interaction box did not have an exit port for the beamline, a new box design became necessary. A decision was made to redesign the plasma chamber from scratch. The proposed design and specifications are described in this note. |
| title: | New design study and related experimental program for the LCLS RF photoinjector |
| conference: | 2000 European Particle Accelerator Conference |
| year: | 2000 |
| authors: | M. Ferrario,P. Bolton,J. Clendenin,D. Dowell,S. Gierman,M. Hernandez,D. Nguyen,D. Palmer,J. Rosenzweig,J. Schmerge,L. Serafini |
| abstract: | We report the results of a recent beam dynamics study, motivated by the need to redesign the LCLS photoinjector, that lead to the discovery of a new effective working point for a split RF photoinjector. We consider the emittance compensation regime of a space charge beam: by increasing the solenoid strength, the emittance evolution shows a double minimum behavior in the drifting region. If the booster is located where the relative emittance maximum and the envelope waist occur, the second emittance minimum can be shifted to the booster exit and frozen at a very low level (0.3 mm-mrad for a 1 nC flat top bunch), to the extent that the invariant envelope matching conditions are satisfied. Standing Wave Structures or alternatively Traveling Wave Structures embedded in a Long Solenoid are both candidates as booster linac. A careful measurement of the emittance evolution as a function of position in the drifting region is necessary to verify the computation and to determine experimentally the proper position of the booster cavities. The new design study and supporting experimental program under way at the SLAC Gun Test Facility are discussed. |
| title: | Non-Resonant Beat-Wave Excitation of Constant Phase-Velocity, Relativistic Plasma Waves for Charged-Particle Acceleration |
| format: | preprint |
| year: | 2003 |
| authors: | C. Filip,R. Narang,S. Tochitsky,C. Clayton,P. Musumeci,R. Yoder,K. Marsh,J. Rosenzweig,C. Pellegrini,C. Joshi |
| abstract: |
| title: | Non-equilibrium transverse motion and emittance growth in space-charge dominated beams |
| conference: | APS April Meeting |
| year: | 2000 |
| authors: | S. Anderson,J. Rosenzweig |
| abstract: | The transverse dynamics of space-charge dominated beams are investigated both analyitically and computationally, in order to understand the mechanisms for emittance oscillations and growth due to nonlinear space-charge fields. This work explores the role of space-charge dominated equilibrium and its relationship to phase space wave-breaking, which is responsible for the irreversible emittance growth in these systems. The physics of both coasting and accelerating beams are examined, in order to illuminate the most effective approaches to beam handling during the emittance compensation process, as well as during subsequent beam transport. |
| title: | Nonequilibrium transverse motion and emittance growth in space-charge dominated beams |
| conference: | 2nd ICFA Advanced Accelerator Workshop on the Physics of High Brightness Beams |
| year published: | 2000 |
| year authored: | 1999 |
| authors: | S. Anderson,J. Rosenzweig |
| abstract: | The transverse dynamics of space-charge dominated beams are investigated both analytically and computationally, in order to understand the mechanisms for emittance oscillations and growth due to nonlinear space-charge fields. This work explores the role of space-charge dominated equilibrium and its relationship to phase space wave-breaking, which is responsible for the irreversible emittance growth in these systems. The physics of both coasting and accelerating beams are examined, in order to illuminate the most effective approaches to beam handling during the emittance compensation process, as well as during subsequent beam transport. (13 References). |
| title: | Nonequilibrium transverse motion and emittance growth in ultrarelativistic space-charge dominated beams |
| journal: | Physical Review Special Topics-Accelerators & Beams |
| vol-pages: | 094201 |
| year: | 2000 |
| authors: | S. Anderson,J. Rosenzweig |
| abstract: | The transverse dynamics of space-charge dominated beams are investigated both analytically and computationally, in order to understand the mechanisms for emittance oscillations and growth due to nonlinear space-charge fields. This work explores the role of space-charge dominated equilibrium and its relationship to phase space wave breaking, which is responsible for the irreversible emittance growth in these systems. The physics of both coasting and accelerating beams are examined in order to illuminate the most effective approaches to beam handling during the emittance compensation process as well as during subsequent beam transport. These results are discussed within the context of recent ultrahigh brightness RF photoinjector designs. (20 References). |
| title: | Nonlinear Plasma Dynamics in the Plasma Wakefield Accelerator |
| journal: | IEEE Transactions on Plasma Science |
| vol-pages: | 186-91 |
| year: | 1987 |
| authors: | J. Rosenzweig |
| abstract: |
| title: | Nonlinear beam dynamics experimental program at SPEAR |
| conference: | Workshop on Nonlinear Dynamics in Particle Accelerators: Theory and Experiments |
| year published: | 1995 |
| year authored: | 1994 |
| authors: | P. Tran,C. Pellegrini,M. Cornacchia,M. Lee,W. Corbett |
| abstract: | Since nonlinear effects can impose strict performance limitations on modern colliders and storage rings, future performance improvements depend on further understanding of nonlinear beam dynamics. Experimental studies of nonlinear beam motion in three-dimensional space have begun in SPEAR using turn-by-turn transverse and longitudinal phase-space monitors. This paper presents preliminary results from an on-going experiment in SPEAR. (10 References). |
| title: | Nonlinear plasma and beam physics in plasma wake-fields |
| conference: | Conference on Nonlinear and Relativistic Effects in Plasmas |
| year published: | 1992 |
| year authored: | 1990 |
| authors: | J. Rosenzweig |
| abstract: | In experimental studies of the plasma wake-field accelerator performed to date at the Argonne Advanced Accelerator Test Facility, significant nonlinearities in both plasma and beam behavior have been observed. The plasma waves driven in the wake of the intense driving beam in these experiments exhibit three-dimensional nonlinear behavior which has as yet no quantitative theoretical explanation. This nonlinearity is due in part to the self-pinching of the driving beam in the plasma, as the denser self-focused beam can excite larger amplitude plasma waves. The self-pinching is a process with interesting nonlinear aspects: the initial evolution of the beam envelope and the subsequent approach to Bennett equilibrium through phase mixing. (35 References). |
| title: | Nonlinear plasma dynamics in the plasma wake-field accelerator |
| journal: | Physical Review Letters |
| vol-pages: | 555-8 |
| year: | 1987 |
| authors: |