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C. Pellegrini

First Name: Claudio

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Last Name: Pellegrini

Full Name: C. Pellegrini

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268 papers
title: High efficiency, multiterawatt x-ray free electron lasers
format: journal article
publisher: Physical Review Accelerators and Beams
year: 2016
4 authors: C. Emma | K. Fang | J. Wu | C. Pellegrini
abstract: In this paper we present undulator magnet tapering methods for obtaining high efficiency and multiterawatt peak powers in x-ray free electron lasers (XFELs), a key requirement for enabling 3D atomic resolution single molecule imaging and nonlinear x-ray science. The peak power and efficiency of tapered XFELs is sensitive to time dependent effects, like synchrotron sideband growth. To analyze this dependence in detail we perform a comparative numerical optimization for the undulator magnetic field tapering profile including and intentionally disabling these effects. We show that the solution for the magnetic field taper profile obtained from time independent optimization does not yield the highest extraction efficiency when time dependent effects are included. Our comparative optimization is performed for a novel undulator designed specifically to obtain TW power x-ray pulses in the shortest distance: superconducting, helical, with short period and built-in strong focusing. This design reduces the length of the breaks between modules, decreasing diffraction effects, and allows using a stronger transverse electron focusing. Both effects reduce the gain length and the overall undulator length. We determine that after a fully time dependent optimization of a 100 m long Linac coherent light source-like XFEL we can obtain a maximum efficiency of 7%, corresponding to 3.7 TW peak radiation power. Possible methods to suppress the synchrotron sidebands, and further enhance the FEL peak power, up to about 6 TW by increasing the seed power and reducing the electron beam energy spread, are also discussed.
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title: HIGH EFFICIENCY, HIGH BRIGHTNESS X-RAY FREE ELECTRON LASERS VIA FRESH BUNCH SELF-SEEDING
format: conference proceeding
conference: IPAC 2016
year: 2016
6 authors: C. Emma | C. Pellegrini | A. Lutman | M. Guetg | A. Marinelli | J. Wu
abstract: High efficiency, terawatt peak power X-ray Free Electron Lasers (XFELs) are a promising tool for enabling 3D atomic resolution single molecule imaging and nonlinear science using X-ray beams. Increasing the efficiency of XFELs while maintaining good longitudinal coherence can be achieved via self-seeding and tapering the undulator magnetic field. The efficiency of tapered self seeded XFELs is limited by two factors: the ratio of seed power to beam energy spread and the ratio of seed power to electron beam shot noise. We present a method to overcome these limitations by producing a strong X-ray seed and amplifying it with a small energy spread electron bunch. This can be achieved by selectively suppressing lasing for part of the electron beam in the SASE section and using the rest of the bunch to generate the seed radiation. In this manner one can reach saturation with the seeding electrons and the strong seed pulse can be overlapped with the “fresh" electrons downstream of the self-seeding monochromator. Simulations of this scenario demonstrating an increased efficiency are presented for two systems, an optimal superconducting undulator design and the Linac Coherent Light Source. In the case of the LCLS we examine how the betatron oscillations leading to selective suppression can be induced by using the transverse wakefield of a parallel plate corrugated structure, a dechirper.
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title: TAPERING STUDIES FOR TW LEVEL X-RAY FELS WITH A SUPERCONDUCTING UNDULATOR AND BUILT-IN FOCUSING
format: conference proceeding
conference: FEL 2015 37th
year: 2015
4 authors: C. Emma | C. Pellegrini | K. Fang | J. Wu
abstract: Tapering optimization schemes for TeraWatt (TW) level X-ray Free Electron Lasers (FELs) are critically sensitive to the length of individual undulator and break sections. Break sections can be considerably shortened if the focusing quadrupole field is superimposed on the undulator field, increasing the filling factor and the overall extraction efficiency of the tapered FEL. Furthermore, distributed focusing reduces the FODO length and allows one to use smaller beta functions, reducing particle de-trapping due to betatron motion from the radial tails of the electron beam. We present numerical calculations of the tapering optimization for such an undulator using the three dimensional time dependent code GENESIS. Time dependent simulations show that 8 keV photons can be produced with over 3 TW peak power in a 100m long undulator. We also analyze in detail the time dependent effects leading to power saturation in the taper region. The impact of the synchrotron sideband growth on particle detrapping and taper saturation is discussed. We show that the optimal taper profile obtained from time independent simulation does not yield the maximum extraction efficiency when multi-frequency effects are included. A discussion of how to incorporate these effects in a revised model is presented.
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title: FEMTOSECOND X-RAY PULSE GENERATION WITH AN ENERGY CHIRPED ELECTRON BEAM
format: conference proceeding
conference: FEL 2015 37th
year: 2015
7 authors: C. Emma | C. Pellegrini | Y. Ding | G. Marcus | A. Lutman | Z. Huang | A. Marinelli
abstract: We study the generation of short (sub 10 fs) pulses in the X-ray spectral region using an energy chirped electron beam in a Self Amplified Spontaneous Emission Free Electron Laser (SASE FEL) and a self-seeding monochromator [1-4]. The monochromator filters a small bandwidth, short duration pulse from the frequency chirped SASE spectrum. This pulse is used to seed a small fraction of the long chirped beam, hence a short pulse with narrow bandwidth is amplified in the following undulators. We present start-to-end simulation results for LCLS operating in the soft X-ray self-seeded mode with an energy chirp of 1% over 30 fs and a bunch charge of 150 pC. We show the possibility to generate 5 fs pulses with a bandwidth 0.3 eV. We also assess the possibility of further shortening the pulse by utilizing one more chicane after the self-seeding stage and shifting the radiation pulse to a “fresh” part of the electron beam. Experimental study on this short pulse seeding mode has been planned at the LCLS.
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title: Terawatt x-ray free-electron-laser optimization by transverse electron distribution shaping
format: journal article
publisher: Physical Review Accelerators and Beams
year: 2014
6 authors: C. Emma | J. Wu | K. Fang | S. Chen | S. Serkez | C. Pellegrini
abstract: We study the dependence of the peak power of a 1.5 Å Terawatt (TW), tapered x-ray free-electron laser (FEL) on the transverse electron density distribution. Multidimensional optimization schemes for TW hard x-ray free-electron lasers are applied to the cases of transversely uniform and parabolic electron beam distributions and compared to a Gaussian distribution. The optimizations are performed for a 200 m undulator and a resonant wavelength of λr=¼1.5Å using the fully three-dimensional FEL particle code GENESIS. The study shows that the flatter transverse electron distributions enhance optical guiding in the tapered section of the undulator and increase the maximum radiation power from a maximum of 1.56 TW for a transversely Gaussian beam to 2.26 TW for the parabolic case and 2.63 TW for the uniform case. Spectral data also shows a 30% – 70% reduction in energy deposited in the sidebands for the uniform and parabolic beams compared with a Gaussian. An analysis of the transverse coherence of the radiation shows the coherence area to be much larger than the beam spotsize for all three distributions, making coherent diffraction imaging experiments possible.
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title: RADIATION PROPERTIES OF TAPERED HARD X-RAY FREE ELECTRON LASERS
format: conference proceeding
conference: FEL 2014 36th
year: 2014
6 authors: C. Emma | C. Pellegrini | J. Wu | K. Fang | S. Chen | S. Serkez
abstract: We perform an analysis of the transverse coherence of the radiation from a TW level tapered hard X-ray Free Electron Laser (FEL). The radiation properties of the FEL are studied for a Gaussian, parabolic and uniform transverse electron beam density profile in a 200 m undulator at a resonant wavelength of 1.5 Å. Simulations performed using the 3-D FEL particle code GENESIS show that diffraction of the radiation occurs due to a reduction in optical guiding in the tapered section of the undulator. This results in an increasing transverse coherence for all three transverse electron beam profiles. We determine that for each case considered the radiation coherence area is much larger than the electron beam spot size, making coherent diffraction imaging experiments possible for TW X-ray FELs.
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title: TW X-RAY FREE ELECTRON LASER OPTIMIZATION BY TRANSVERSE PULSE SHAPING
format: conference proceeding
conference: FEL 2014 36th
year: 2014
3 authors: C. Emma | C. Pellegrini | J. Wu
abstract: We study the dependence of the peak power of a 1.5 Å TW, tapered X-ray free-electron laser on the transverse electron density distribution. Multidimensional optimization schemes for TW hard X-Ray free electron lasers are applied to the cases of transversely uniform and parabolic electron beam distributions and compared to a Gaussian distribution. The optimizations are performed for a 200 m undulator using the fully 3-dimensional FEL particle code GENESIS. The study shows that the flatter transverse electron distributions enhance optical guiding in the tapered section of the undulator and increase the maximum radiation power from a maximum of 1.56 TW for a transversely Gaussian beam to 2.26 TW for the parabolic case and 2.63 TW for the uniform case.
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title: Breaking the Attosecond, Angstrom and TV/m Field Barriers with Ultrafast Electron Beams
format: conference proceeding
conference: AAC 2010 14th
year: 2010
17 authors: J.B. Rosenzweig | G. Andonian | P. Bucksbaum | A. Fukasawa | M. Ferrario | M. Hogan | E. Hemsing | P. Krejcik | G. Marcus | A. Marinelli | P. Muggli | P. Musumeci | B. O'Shea | F. O'Shea | C. Pellegrini | D. Schiller | G. Travish
abstract: Recent initiatives at UCLA concerning ultra-short, GeV electron beam generation have been aimed at achieving sub-fs pulses capable of driving X-ray free-electron lasers (FELs) in single-spike mode. This scheme uses very low charge beams, which may allow existing FEL injectors to produce few-100 attosecond pulses, with very high brightness. Towards this end, recent experiments at the Stanford X-ray FEL (LCLS, first of its kind, built with essential UCLA leadership) have produced ~2 fs, 20 pC electron pulses. We discuss here extensions of this work, in which we seek to exploit the beam brightness in FELs, in tandem with new developments at UCLA in cryogenic undulator technology, to create compact accelerator/undulator systems that can lase below 0.15 Å, or be used to permit 1.5 Å operation at 4.5 GeV. In addition, we are now developing experiments which use the present LCLS fs pulses to excite plasma wakefields exceeding 1 TV/m, permitting a table-top TeV accelerator for frontier high energy physics applications. We discuss the experimental issues associated with this initiative.
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title: Status of the SPARC-X Project
format: conference proceeding
conference: PAC 2007
year: 2007
97 authors: C. Vaccarezza | D. Alesini | M. Bellaveglia | S. Bertolucci | R. Boni | M. Boscolo | M. Castellano | A. Clozza | L. Cultrera | G. Di Pirro | A. Drago | A. Esposito | M. Ferrario | L. Ficcadenti | D. Filippetto | V. Fusco | A. Gallo | G. Gatti | A. Ghigo | C. Ligi | Agostino Marinelli | M. Migliorati | A. Mostacci | E. Pace | L. Palumbo | L. Pellegrino | M. Preger | R. Ricci | C. Sanelli | M. Serio | F. Sgamma | B. Spataro | A. Stella | F. Tazzioli | M. Vescovi | C. Vicario | F. Ciocci | G. Dattoli | A. Dipace | A. Doria | F. Flora | G.P. Gallerano | L. Giannessi | E. Giovenale | G. Messina | P.L. Ottaviani | S. Pagnutti | G. Parisi | L. Picardi | M. Quattromini | A. Renieri | G. Ronci | C. Ronsivalle | M. Rosetti | E. Sabia | M. Sassi | A. Torre | A. Zucchini | M. Mattioli | D. Pelliccia | L. Catani | E. Chiadroni | A. Cianchi | E. Gabrielli | C. Schaerf | P. Musumeci | M. Petrarca | F. Alessandria | A. Bacci | R. Bonifacio | I. Boscolo | F. Broggi | C. De Martinis | F. Castelli | S. Cialdi | D. Giove | A. Flacco | C. Maroli | V. Petrillo | A.R. Rossi | L. Serafini | A. Perrone | M. Labat | O. Tcherbakoff | G. Lambert | D. Garzella | M. Bougeard | P. Breger | P. Monchicourt | H. Merdji | P. Salie?res | B. Carre? | M. E. Couprie | P. Emma | C. Pellegrini | S. Reiche | J.B. Rosenzweig
abstract: SPARC-X is a two branch project consisting in the SPARC test facility dedicated to the development and test of critical subsystems such as high brightness photoinjector and a modular expandable undulator for SASE-FEL experiments at 500 nm with seeding, and the SPARX facility aiming at generation of high brilliance coherent radiation in the 1.5-13 nm range, based on the achieved expertise. The projects are supported by MIUR (Research Department of Italian Government) and Regione Lazio. SPARC has completed the commissioning phase of the photoinjector in November 2006. The achieved experimental results are here summarized together with the status of the second phase commissioning plans. The SPARX project is based on the generation of ultra high peak brightness electron beams at the energy of 1 and 2 GeV generating radiation in the 1.5-13 nm range. The construction is at the moment planned in two steps starting with a 1 GeV Linac. The project layout including both RF-compression and magnetic chicane techniques has been studied.
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title: Seeded free-electron and inverse free-electron laser techniques for radiation amplification and electron microbunching in the terahertz range
format: journal article
publisher: Physical Review Letters
year: 22 December 2006
6 authors: C. Sung | S. Ya. Tochitsky | S. Reiche | J.B. Rosenzweig | C. Pellegrini | C. Joshi
abstract: A comprehensive analysis is presented that describes amplification of a seed THz pulse in a single-pass free-electron laser (FEL) driven by a photoinjector. The dynamics of the radiation pulse and the modulated electron beam are modeled using the time-dependent FEL code, GENESIS 1.3. A 10-ps (FWHM) electron beam with a peak current of 50100 A allows amplification of a 1 kWseed pulse in the frequency range 0.53 THz up to 10100 MW power in a relatively compact 2-m long planar undulator. The electron beam driving the FEL is strongly modulated, with some inhomogeneity due to the slippage effect. It is shown that THz microbunching of the electron beam is homogeneous over the entire electron pulse when saturated FEL amplification is utilized at the very entrance of an undulator. This requires seeding of a 30-cm long undulator buncher with a 13 MW of pump power with radiation at the resonant frequency. A narrow-band seed pulse in the THz range needed for these experiments can be generated by frequency mixing of CO2 laser lines in a GaAs nonlinear crystal. Two schemes for producing MW power pulses in seeded FELs are considered in some detail for the beam parameters achievable at the Neptune Laboratory at UCLA: the first uses a waveguide to transport radiation in the 0.53 THz range through a 2-m long FEL amplifier and the second employs high-gain third harmonic generation using the FEL process at 39 THz.
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title: Future FEL Studies at the VISA Experiment in the SASE and Seeded Modes
format: journal article
publisher:
year: 2006
9 authors: G. Andonian | M.P. Dunning | A. Y. Murokh | C. Pellegrini | S. Reiche | J.B. Rosenzweig | M. Babzien | I. Ben-Zvi | V. Yakimenko
abstract: The VISA (Visible to Infrared SASE Amplifier) experiment at BNL (Brookhaven National Laboratory) has previously demonstrated saturation at 840 nm in 2001. Further SASE studies, in 2003, have demonstrated an anomalously large bandwidth spread of the FEL spectrum due to off-angle emissions. This paper disseminates the current and future program of the VISA program at BNL. This includes a study of a seeded FEL, using a 1 micron YAG laser as a seed, and the accompanying diagnostics to characterize the radiation. Diagnostics include the double differential spectrometer, a mode converter to investigate the orbital angular momentum of light in the FEL, and an optical pepper-pot for coherence measurements. As usual, start-to-end simulations are presented.
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title: Development of a Waveguide FEL Seeded in the 1-3 THz Range for Microbunching Experiment at the Neptune Laboratory
format: conference proceeding
conference: AAC 2006 12th
year: 2006
8 authors: C. Sung | S. Ya. Tochitsky | S. Reiche | S. C. Gottschalk | W. D. Kimura | J.B. Rosenzweig | C. Pellegrini | C. Joshi
abstract: IFEL and FEL techniques can be used to modulate an electron beam on the scale of the radiation wavelength. However, the lack of a high power radiation source in the 100-300 ?m range hinders the progress on THz IFEL microbunching. In this paper, we discuss microbunching of an electron beam using a single-pass FEL seeded with a low power THz pulse generated by frequency mixing of CO2 laser lines in a GaAs nonlinear crystal. A narrowband THz seed source is pumped by a dual beam TEA CO2 laser and can be tuned in the 1-3 THz range. The THz radiation is guided through a hollow waveguide inside the planar FEL undulator driven by a photoinjector. By using a time-dependent FEL code GENESIS 1.3, we optimized the undulator parameters and analyzed the dynamics of the modulated electron beam. By using a ~ 8 MeV electron beam with a peak current of 40 A and a ~1kW THz seed with wavelength 200 ?m, the energy modulation up to 1.3% can be achieved in a ~1.8-m long undulator with a constant period of 2.7 cm. At present, the THz seed source is built and fully characterized. The results of transmission measurements for THz waveguides are also discussed.
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title: LASER BEAT-WAVE MICROBUNCHING OF RELATIVISTIC ELECTRON BEAM IN THE THZ RANGE
format: conference proceeding
conference: Linear Accelerator Conference 2006
year: 2006
6 authors: S. Ya. Tochitsky | S. Reiche | C. Sung | J.B. Rosenzweig | C. Pellegrini | C. Joshi
abstract: Laser-driven plasma accelerators have recently demonstrated a ~1GeV energy gain of self-trapped electrons in a several-centimeter-long plasma channel. Potential staging of such devices will require the external injection of an electron beam prebunched on the scale of 1-10 THz into a plasma accelerating structure or plasma LINAC. Seeded FEL/IFEL techniques can be used for modulation of the electron beam longitudinally on the radiation wavelength scale. However, a seed source in this spectral range is not available. At the UCLA Neptune Laboratory a Laser Beat-Wave (LBW) microbunching experiment has begun. The interaction of the electron beam and the LBW results in ponderomotive acceleration and energy modulation on the THz scale. This stage is followed by a ballistic drift of the electrons, where the gained energy modulation is transferred to the beam current modulation. Then the beam is sent into a 33-cm long undulator, where a coherent start-up of THz radiation takes place, and the THz pulse is used for a bunching analysis. The performance of LBW bunching is simulated and analyzed using a 3D FEL code for the parameters of an existing photoinjector and two-wavelength TW CO2 laser system.
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title: Simulations, Diagnostics and Recent Results of the VISA II Experiment
format: conference proceeding
conference: FEL 2005 27th
year: August 2005
17 authors: G. Andonian | A. Murokh | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | G. Travish | M. Babzien | I. Ben-Zvi | V. Litvinenko | V. Yakimenko | I. Boscolo | S. Cialdi | A. Flacco | M. Ferrario | L. Palumbo | C. Vicario | J. Huang
abstract: The VISA II experiment entails the use of a chirped electron beam to drive a high gain SASE FEL. Sextupoles are implemented to correct the longitudinal aberrations affecting the high energy spread chirped beam during transport to the undulator. The output radiation is diagnosed with a modified frequency resolved optical gating (FROG) technique. The double differential energy spectrum is measured with a pair of slits and a set of gratings. In this paper, we report on start-to-end simulations, radiation diagnostics, as well as initial experimental results. Technical considerations for future experimental methods are also addressed.
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title: Observation of Anomalously Large Spectral Bandwidth in a High-Gain Self-Amplified Spontaneous Emission Free Elctron Laser
format: journal article
publisher: Physical Review Letters
year: 2005
14 authors: G. Andonian | A. Murokh | J.B. Rosenzweig | R. Agustsson | M. BABZIEN | I. Ben-Zvi | P. Frigola | J.Y. Huang | L. Palumbo | C. Pellegrini | Sven Reiche | G. Travish | C. Vicario | V. Yakimenko
abstract: Observation of ultrawide bandwidth, up to 15% full-width, high-gain operation of a self-amplified spontaneous emission free-election laser (SASE FEL) is reported. This type of lasing is obtained with a strongly chirped beam (E=E  1:7%) emitted from the accelerator. Because of nonlinear pulse compression during transport, a short, high current bunch with strong mismatch errors is injected into the undulator, giving high FEL gain. Start-to-end simulations reproduce key features of the measurements and provide insight into mechanisms, such as angular spread in emitted photon and electron trajectory distributions, which yield novel features in the radiation spectrum.
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title: High Energy Gain of Trapped Electrons in a Tapered, Diffraction-Dominated Inverse-Free-Electron Laser
format: preprint
year: 2005
16 authors: P. Musumeci | S. Boucher | A. Doyuran | R. J. England | C. Pellegrini | J.B. Rosenzweig | G. Travish | R. B. Yoder | S. Ya. Tochitsky | C. E. Clayton | C. Joshi | J. E. Ralph | C. Sung | S. Tolmachev | A. A. Varfolomeev | T. Yarovoi
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.
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title: Recent Results from and Future Plans for the VISA II SASE FEL
format: conference proceeding
conference: PAC 2005
year: 2005
19 authors: G. Andonian | R. Agustsson | P. Frigola | A. Murokh | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | G. Travish | M. BABZIEN | I. Ben-Zvi | V. Litvinenko | V. Yakimenko | I. Boscolo | S. Cialdi | A. Flacco | M. Ferrario | L. Palumbo | C. Vicario | J. Huang
abstract: The VISA II (Visible to Infrared SASE Amplifier) project, a consequent experiment to the succesful VISA enterprise, entails the use of a chirped electron beam to drive a high gain SASE FEL. The resulting ultra-short pulses will be characterized using an advanced FROG (Frequency Resolved Optical Gating) technique, as well as a double differential spectrum (angle/wavelength) diagnostic. Implementation of sextupole corrections to the longitudinal aberrations affecting the high energy-spread chirped beam during transport to the VISA undulator is studied. Start-end simulations, including radiation diagnostics, are discussed. Initial experimental results involving a highly chirped beam transported without sextupole corrections, the resulting high gain lasing, and computational analysis are briefly reported.
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title: Recent Results from and Future Plans for the VISA II SASE FEL
format: preprint
year: 2005
19 authors: G. Andonian | R. Agustsson | Pedro Frigola | A. Murokh | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | G. Travish | M. BABZIEN | I. Ben-Zvi | V. Litvinenko | V. Yakimenko | I. Boscolo | S. Cialdi | A. Flacco | M. Ferrario | L. Palumbo | C. Vicario | J. Huang
abstract: The VISA II (Visible to Infrared SASE Amplifier) project, a consequent experiment to the succesful VISA enterprise, entails the use of a chirped electron beam to drive a high gain SASE FEL. The resulting ultra-short pulses will be characterized using an advanced FROG (Frequency Resolved Optical Gating)technique, as well as a double differential spectrum (angle/wavelength) diagnostic. Implementation of sextupole corrections to the longitudinal aberrations affecting the high energy-spread chirped beam during transport to the VISA undulator is studied. Start-end simulations, including radiation diagnostics, are discussed. Initial experimental results involving a highly chirped beam transported without sextupole corrections, the resulting high gain lasing, and computational analysis are briefly reported.
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title: Observation of Anomalously Large Spectral Bandwidth in a High Gain Self-amplified Spontaneous Emission Free-Electron Laser
format: preprint
year: 2005
14 authors: G. Andonian | A. Murokh | J.B. Rosenzweig | R. Agustsson | M. Babzien | I. Ben-Zvi | Pedro Frigola | J. Huang | L. Palumbo | C. Pellegrini | Sven Reiche | G. Travish | C. Vicario | V. Yakimenko
abstract: Observation of ultra-wide bandwidth, up to a full width of 15%, high-gain operation of a self-amplified spontaneous emission free election laser (SASE FEL) is reported. This type of lasing is obtained with a strongly chirped beam (~ 1.7%) emitted from the accelerator. Because of non-linear pulse compression during beam transport, a short, high current pulse with strong mismatch errors is injected into the undulator, bringing about high FEL gain. Start-end simulations reproduce key features of the measured results, and provide insight into mechanisms, such as angular spread in both emitted photon and electron trajectory distributions, which yield novel features in the radiation spectrum.
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title: Higher harmonic inverse free-electron laser interaction
format: journal article
publisher: Physical Review E
year: 2005
3 authors: P. Musumeci | C. Pellegrini | J.B. 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.
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title: Traveling wave undulators for FELs andsynchrotron radiation sources.
format: preprint
year: 2005
1 author: C. Pellegrini
abstract: We study the use of a traveling wave waveguide as an undulator for short wavelength free-electron lasers (FELs) and synchrotron radiation sources. This type of undulator -which we will call TWU- can be useful when a short electron oscillation period and a large aperture for the propagation of the beam are needed. The availability of high power X-band microwave sources, developed for the electron-positron linear collider, make it possible today to build TWUs of practical interest to produce short wavelength radiation from a beam of reduced energy respect to the case of more conventional undulators. In this paper we will discuss the characteristic of the TWU, the systems that can be used to control the effect of RF power losses in the waveguide walls, and how to optimize a TWU and the associated electron transport system for use in a synchrotron radiation source or FEL.
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title: A Coherent Compton Backscattering High Gain FEL Using an X-Band Microwave Undulator
format: conference proceeding
conference: FEL 2005 27th
year: 2005
6 authors: S. Tantawi | V. Dolgashev | C. Nantista | C. Pellegrini | J.B. Rosenzweig | G. Travish
abstract: High power microwave sources at X-Band, delivering 400 to 500 of megawatts for about 400 ns, have been recently developed. These sources can power a microwave undulator with short period and large gap, and can be used in short wavelength FELs reaching the nm region at a beam energy of about 1 GeV. We present here an experiment designed to demonstrate that microwave undulators have the field quality needed for high gain FELs. compensate RF power losses, it might be convenient to have an open waveguide geometry, as will be discussed later in the paper. However the initial FEL calculations are based on a circular cross-section waveguide. The undulator is powered by two transverse electric modes, shifted in the time phase by
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title: High Energy gain IFEL at the UCLA Neptune Laboratory
format: journal article
publisher:
year: 2005
16 authors: P. Musumeci | S. Ya. Tochitsky | S. Boucher | A. Doyuran | R. J. England | C. Joshi | C. Pellegrini | J. Ralph | J.B. Rosenzweig | C. Sung | G. Travish | R. Yoder | A. A. Varfolomeev | S. Tolmachev | A. Varfolomeev Jr. | T. Yarovoi
abstract: We report on the observation of energy gain in excess of 20MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5MeV electron beam is injected in a 50cm longundulator strongly tapered both in period and field amplitude. A CO210.6?m laser with power > 400GW is used as the IFEL driver. The Rayleigh range of the laser(?1.8cm)is shorter than the undulator length so that the interaction is diffraction dominated. Few per cent of the injected particles are trapped instable accelerating buckets and electrons with energies up to 35 MeV are detected on the magnetic spectrometer. Three dimensional simulations are in good agreement with the electron energy spectrums observed in the experiment and indicate that substantial energy exchange between laser and electron beam only occurs in the first 25-30 cm of the undulator. Anenergygradientof>70MeVisinferred. In these cond section of the undulator higher harmonic IFEL interaction is observed.
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title: Feasibility Study of a Laser Beat-Wave Seeded THz FEL at the Neptune Laboratory
format: conference proceeding
conference: PAC 2005
year: 2005
6 authors: S. Reiche | C. Joshi | C. Pellegrini | J.B. Rosenzweig | S. Tochitsky | G. Shvets
abstract: Free-Electron Laser in the THz range can be used to generate high output power radiation or to modulate the electron beam longitudinally on the radiation wavelength scale. Microbunching on the scale of 1-5 THz is of partic- ular importance for potential phase-locking of a modulated electron beam to a laser-driven plasma accelerating struc- ture. However the lack of a seeding source for the FEL at this spectral range limits operation to a SASE FEL only, which denies a subpicosecond synchronization of the cur- rent modulation or radiation with an external laser source. One possibility to overcome this problem is to seed the FEL with two external laser beams, which difference (beat- wave) frequency is matched to the resonant FEL frequency in the THz range. In this presentation we study feasibility of an experiment on laser beat-wave injection in the THz FEL considered at the UCLA Neptune Laboratory, where both a high brightness photoinjector and a two-wavelength, TW-class CO2 laser system exist. By incorporating the energy modulation of the electron beam by the pondero- motive force of the beat-wave in a modified version of the time-dependent FEL code Genesis 1.3, the performance of a FEL at Neptune is simulated and analyzed.
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title: Terahertz IFEL/FEL Microbunching for Plasma Beatwave Accelerators
format: journal article
publisher:
year: 2005
9 authors: C. Sung | S. Ya. Tochitsky | J. Ralph | P. Musumeci | S. Reiche | C. Clayton | J.B. Rosenzweig | C. Pellegrini | C. Joshi
abstract: In order to obtain monoenergetic acceleration of electrons, phase-locked injection using electron microbunches shorter than the accelerating structure is necessary. For a laser-driven plasma beatwave accelerator experiment, we propose to microbunch the electrons by interaction with terahertz (THz) radiation in an undulator via two mechanisms� Free Electron Laser (FEL) and Inverse Free Electron Laser (IFEL). Since the high power FIR radiation will be generated via difference frequency mixing in GaAs by the same CO2 beatwave used to drive the plasma wave, electrons could be phase-locked and pre-bunched into a series of microbunches separated with the same periodicity. Here we examine the criteria for undulator design and present simulation results for both IFEL and FEL approaches. Using different CO2 laser lines, electrons can be microbunched with different periodicity 300 �100 ?m suitable for injection into plasma densities in the range 1016 � 1017 cm-3, respectively. The requirements on the THz radiation power and the electron beam qualities are also discussed.
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title: High Energy Gain of Trapped Electrons in a Tapered, Diffraction-Dominated Inverse-Free-Electron Laser
format: journal article
publisher: Physical Review Letters
year: 20 April 2005
17 authors: P. Musumeci | S. Ya. Tochitsky | S. Boucher | C. Clayton | A. Doyuran | R. J. England | C. Joshi | C. Pellegrini | J. E. Ralph | J.B. Rosenzweig | C. Sung | Tolmachev, S. | G. Travish | A. A. Varfolomeev | A. A. Varfolomeev | T. Yarovoi | R. B. 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.
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title: Very High Energy Gain at the Neptune Inverse Free Electron Laser Experiment
format: journal article
publisher: AIP Conference Proceedings
year: Dec 2004
16 authors: P. Musumeci | S. Ya. Tochitsky | S. Boucher | A. Doyuran | R. J. England | C. Joshi | C. Pellegrini | J. Ralph | J.B. Rosenzweig | C. Sung | S. Tolmachev | G. Travish | A. A. Varfolomeev | A. Varfolomeev Jr. | T. Yarovoi | R. Yoder
abstract: We report the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in an undulator strongly tapered in period and field amplitude. The IFEL driver is a CO2 10.6 m laser with power larger than 400 GW. The Rayleigh range of the laser, ~ 1.8 cm, is much shorter than the undulator length so that the interaction is diffraction dominated. A few per cent of the injected particles are trapped in a stable accelerating bucket. Electrons with energies up to 35 MeV are measured by a magnetic spectrometer. Three-dimensional simulations, in good agreement with the measured electron energy spectrum, indicate that most of the acceleration occurs in the first 25 cm of the undulator, corresponding to an energy gradient larger than 70 MeV/m. The measured energy spectrum also indicates that higher harmonic Inverse Free Electron Laser interaction takes place in the second section of the undulator.
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title: Conceptual Design for a 1-GeV IFEL Accelerator
format: journal article
publisher: AIP Conference Proceedings
year: Dec 2004
5 authors: W. D. Kimura | P. Musumeci | D. C. Quimby | S. C. Gottschalk | C. Pellegrini
abstract: A conceptual design for a multistaged 1-GeV IFEL laser-driven accelerator (laser linac) was developed using the Staged Electron Laser Acceleration (STELLA) inverse free electron laser (IFEL) model created at STI Optronics. A comparison with the UCLA TREDI model yields good agreement with the STELLA model. The 1-GeV IFEL laser linac consists of an IFEL buncher for forming microbunches and four IFEL acceleration stages. Electrons enter the laser linac from a conventional microwave-driven linac (51 MeV). The acceleration stages are driven by 10-TW laser beams at 1.06-m. It is found good trapping occurs as the electrons are accelerated; however, refocusing of the e-beam between acceleration stages is needed to control detrapping effects. The energy spread of the trapped electrons is also small. This design exercise was in support of the task placed upon the EM Structure-Based Accelerators Working Group at the 2004 Advanced Accelerator Concepts Workshop. It demonstrates that a 1-GeV IFEL laser linac is feasible with present technology. 2004 American Institute of Physics
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title: A Helical Undulator Wave-guide Inverse Free-Electron Laser
format: conference proceeding
conference: AAC 2004 11th
year: 2004
8 authors: J.B. Rosenzweig | N. Bodzin | P. Frigola | C. Joshi | P. Musumeci | C. Pellegrini | S. Tochitsky | G. 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.
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title: Enhanced Acceleration of Injected Electrons in a Laser Beatwave Induced Plasma Channel
format: preprint
year: 2004
10 authors: S. Ya. Tochitsky | R. Narang | C. V. Filip | P. Musumeci | C. E. Clayton | R. B. Yoder | K. A. Marsh | J.B. Rosenzweig | C. Pellegrini | C. 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
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title: Development of X-ray Free-electron Lasers
format: journal article
publisher: IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS,
year: 2004
2 authors: C. Pellegrini | Sven 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.
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title: The Development of X-ray Free-Electron Lasers
format: journal article
publisher: Selected Topics in Quantum Electronics, IEEE Journal
year: 2004
2 authors: S. Reiche | C. Pellegrini
abstract: We review and discuss the theoretical and experi- mental 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 un- precedented 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. tool to study the properties and structure of matter at the atomic and molecular level for over a century. Using X-rays we have made great progress in understanding the physical properties of materials and living systems. Today, the best sources of X-rays utilize spontaneous synchrotron radiation from relativistic elec- tron beams in storage rings with undulator magnet insertions. The most advanced, so-called third generation sources, are used by thousands of scientists around the world.
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title: VISA IB: Ultra-High Bandwidth, High Gain SASE FEL
format: conference proceeding
conference: FEL 2004 26th
year: 2004
15 authors: G. Andonian | A. Murokh | R. Agustsson | C. Pellegrini | S. Reiche | J.B. Rosenzweig | G. Travish | M. Babzien | I. Ben-Zvi | J. Y. Huang | V. Litvinenko | V. Yakimenko | M. Ferrario | L. Palumbo | C. Vicario
abstract: We report the results of a high energy spread SASE FEL experiment, the intermediary experiment linking the VISA I and VISA II projects. A highly chirped beam (1.7 %) was transported, without corrections of longitudinal aberrations in the ATF dogleg, and injected into the VISA undulator. The ouput radiation displayed an uncharacteristicly large bandwidth (12 %) with extremely stable lasing and mea- sured energy of about 2 ?J . Start-to-end simulations re- produced key features of the experiment and provided an insight into the michanisms giving rise to such a high band- width. These analyses have important implications on the VISA II experiment.
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title: Study of a THz IFEL prebuncher for laser-plasma accelerators
format: journal article
publisher: AIP Conference Proceedings
year: 2004
7 authors: C. Sung | S. Ya. Tochitsky | P. Musumeci | J. Ralph | J.B. Rosenzweig | C. Pellegrini | C. Joshi
abstract: For monoenergetic acceleration of electrons, the injected particles need to be bunched with the same periodicity as the accelerating structure. In a laser-driven plasma beatwave accelerator, the accelerating structure (plasma wave) is phase-locked to the CO2 beat-wave used to drive it. Using the same beat-wave to generate high power FIR radiation via difference frequency mixing in GaAs ensures that the radiation has the same phase relationship as the plasma wave before it saturates and detunes from the pump. Therefore, this radiation can be used to prebunch an existing electron beam based on an Inverse Free Electron Laser (IFEL) concept. Here we report the progress on the proposed THz microbunching experiment in the Neptune laboratory. A 50 cm long prebuncher is optimized using simulation codes for minimum FIR power required. The injected 5ps long electron beam is expected to form a series of 45 m long microbunches containing over 40% of the injected current after 1.6 m drift space following the undulator. Preliminary experimental results on THz generation are also presented.
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title: Acceleration of electrons in a diffraction-dominated IFEL
format: journal article
publisher: FEL
year: 2004
16 authors: P. Musumeci | S. Ya. Tochitsky | S. Boucher | A. Doyuran | R. J. England | C. Joshi | C. Pellegrini | J. Ralph | J.B. Rosenzweig | C. Sung | S. Tolmachev | G. Travish | A. A. Varfolomeev | A. Varfolomeev Jr. | T. Yarovoi | R. Yoder.
abstract: We report on the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator ex- periment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in a 50 cm long undulator strongly tapered both in period and field amplitude. A CO2 10.6 ?m laser with power > 300 GW is used as the IFEL driver. The Rayleigh range of the laser ( ? 1.8 cm) is shorter than the undulator length so that the interaction is diffraction dom- inated. Few per cent of the injected particles are trapped in stable accelerating buckets and electrons with energies up to 35 MeV are detected on the magnetic spectrometer. Three dimensional simulations are in good agreement with the electron energy spectrums observed in the experiment and indicate that substantial energy exchange between laser and electron beam only occurs in the first 25-30 cm of the undulator. An energy gradient of > 70 MeV is inferred. In the second section of the undulator higher harmonic IFEL interaction is observed.
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title: COMMISSIONING OF STRONG TAPERED UNDULATOR DEVELOPED
format: journal article
publisher:
year: 2004
7 authors: S.V. Tolmachev | A. A. Varfolomeev | A. Varfolomeev Jr. | T.V. Yarovoi | P. Musumeci | C. Pellegrini | J.B. Rosenzweig
abstract: Here we describe the manufactured KIAE-2p planar undulator designed for the Inverse Free Electron Laser experiment at the University of California in Los Angeles. New technology enabled to fabricate the installation responding to the stringent requirements on mechanical construction accuracy and magnetic field strong tapering. Results of the magnetic field measurements by different methods are given. The obtained magnetic field maps were used for final simulations of the acceleration process. It is shown that for nominal electron beam and laser beam parameters up to 30% of electrons can be captured and accelerated from initial 14 MeV up to 52 MeV. Special analysis of the undulator acceptances for these parameters is made. It is shown that the acceleration is possible up to energies >30 MeV for rather wide ranges of laser pulse energy, Rayleigh length and e.b. emittance.
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title: Non-Resonant Beat-Wave Excitation of Constant Phase-Velocity, Relativistic Plasma Waves for Charged-Particle Acceleration
format: journal article
publisher:
year: 2004
10 authors: C. V. Filip | R. Narang | S. Ya. Tochitsky | C. E. Clayton | P. Musumeci | R. B. Yoder | K. A. Marsh | J.B. Rosenzweig | C. Pellegrini | C. Joshi
abstract: The nonresonant beat-wave excitation of relativistic plasma waves is studied in two-dimensional simulations and experiments. It is shown through simulations that, as opposed to the resonant case, the accelerating electric fields associated with the nonresonant plasmons are always in phase with the beat-pattern of the laser pulse. The excitation of such nonresonant relativistic plasma waves is shown to be possible for plasma densities as high as 14 times the resonant density. The density fluctuations and the fields associated with these waves have significant magnitudes, facts confirmed experimentally using collinear Thomson scattering and electron injection, respectively. The applicability of these results towards eventual phase-locked acceleration of prebunched and externally injected electrons is discussed.
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title: Experiments on laser driven beatwave acceleration in a ponderomotively formed plasma channel
format: journal article
publisher: Physics of Plasmas
year: 2004
10 authors: S. Ya. Tochitsky | R. Narang | C. V. Filip | P. Musumeci | C. E. Clayton | R. B. Yoder | K. A. Marsh | J.B. Rosenzweig | C. Pellegrini | C. Joshi
abstract: A 10 ps long beam of 12 MeV electrons is externally injected into a ~3-cm long plasma beatwave excited in a laser ionized hydrogen gas. The electrons have been accelerated to 50 MeV with a gradient of ~1.3 GeV/m. It is shown that when the effective plasma wave amplitude-length product is limited by ionization-induced defocusing (IID), acceleration of electrons is significantly enhanced by using a laser pulse with a duration longer than the time required for ions to move across the laser spot size. Both experiments and two-dimensional simulations reveal that, in this case, self-guiding of the laser pulse in a ponderomotively formed plasma channel occurs. This compensates for IID and drives the beatwave over the longer length compared to when such a channel is not present.
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title: Design and Status of the VISA II Experiment
format: conference proceeding
conference: PAC 2003
year: 2003
12 authors: G.Andonian | R.Agustsson | A. Murokh | C.Pellegrini | Sven Reiche | J.B. 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.
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title: Pulse Length Control in an X-Ray FEL by Using Wakefields
format: conference proceeding
conference: PAC 2003
year: 2003
3 authors: Sven Reiche | P. Emma | C. Pellegrini
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.
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title: Theoretical evaluation of the LCLS X-Ray Free-Electron Laser performance
format: conference proceeding
conference: FEL 2003 25th
year: 2003
4 authors: Sven Reiche | C. Pellegrini | P. Emma | Nuhn, H. D.
abstract: In this paper we evaluate the performance of the LCLS FEL, including all known physical effects from the electron source to the undulator exit which determine the X-ray pulse characteristics. The wavelength range considered is from the 15 to 1.5 Angstrom, with an extension to 0.5 Angstrom using the third harmonic. The results of this work have been useful to identify areas in the LCLS design where improvements could be made, thus optimizing the system performance.
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title: Status of the Inverse Free Electron Laser Experiment at the Neptune Laboratory
format: conference proceeding
conference: PAC 2003
year: 2003
10 authors: P. Musumeci | C. Pellegrini | J.B. Rosenzweig | S. Tochitsky | G. Travish | R. Yoder | A. A. Varfolomeev | Tolmachev, S. | A. Varfolomeev Jr. | T. Yarovoi
abstract: We report on the status of the Inverse Free Electron Laser accelerator experiment under construction at the UCLA Neptune Laboratory. This experiment will use a 400 GW CO2 laser to accelerate through a tapered undulator an electron beam from 14.5 MeV up to 55 MeV. The scheme proposed is the diffraction dominated IFEL interaction where the Rayleigh range of the laser beam is 3.5 cm, much shorter than the interaction length (the undulator length is 50 cm). The undulator is strongly tapered in both field and period. The present status of the experiment is reported.
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title: X-ray free-electron lasers- principles, properties and applications
format: journal article
publisher: Nuclear Instruments & Methods in Physics Research
year: 2003
2 authors: C. Pellegrini | J. Stoehr
abstract: With advances in technology, it is now possible to realize the dream of fully coherent X-ray laser.
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title: Start-to-End Simulations for the LCLS X-Ray Free-Electron Laser
format: conference proceeding
conference: FEL 2003 25th
year: 2003
7 authors: Sven Reiche | C. Pellegrini | P. Emma | Nuhn, H. D. | Limborg, C. G. | Borland, M. | W. Fawley
abstract: The LCLS Free-Electron Lasers operates in the wavelength range of 1.5-15 Angstrom, using an electron beam with an energy between 4.5 and 14.5 GeV. The generation of the electron beam, the preservation of its brightness during acceleration and compression, and the amplififcation of the spontaneous radiation within the FEL can only be described by a consistent set of simulation codes. We preset the change in the FEL performance with respect to the LCLS design case, when various effects are included, altering the electron beam distribution and motion (e.g. wake fields, CSR, magnet misalignment or field errors of the undulator field). To distinguish the individual contribution of each effect, multiple start-end simulations are performed, including step by step additional effects and, thus, approaching a more and more realistic model of the LCLS FEL.
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title: Properties of the ultrashort gain length, self-amplified spontaneous emission free-electron laser in the linear regime and saturation
format: journal article
publisher: Physical Review E
year: 2003
26 authors: A. Murokh | R. Agustsson | M. Babzien | I. Ben-Zvi | L. Bertolini | K. van Bibber | R. Carr | M. Cornacchia | P. Frigola | J. Hill | E. Johnson | L. Klaisner | G.P. Le Sage | M. Libkind | R. Malone | H-D. Nuhn | C. Pellegrini | Sven Reiche | G. Rakowsky | J.B. Rosenzweig | Ruland, R. | Skaritka, J. | A. Toor | A. Tremaine | X. Wang | V. Yakimenko
abstract: VISA (Visible to Infrared SASE Amplifier) is a high-gain self-amplified spontaneous emission (SASE) free-electron laser (FEL), which achieved saturation at 840 nm within a single-pass 4-m undulator. The experiment was performed at the Accelerator Test Facility at BNL, using a high brightness 70-MeV electron beam. A gain length shorter than 18 cm has been obtained, yielding a total gain of 2x10(8) at saturation. The FEL performance, including the spectral, angular, and statistical properties of SASE radiation, has been characterized for different electron beam conditions. Results are compared to the three-dimensional SASE FEL theory and start-to-end numerical simulations of the entire injector, transport, and FEL systems. An agreement between simulations and experimental results has been obtained at an unprecedented level of detail.
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title: Acceleration of Injected Electrons In A Laser Beatwave Experiment
format: conference proceeding
conference: PAC 2003
year: 2003
10 authors: S. Ya. Tochitsky | R. Narang1 | C.V. Filip1 | P. Musumeci | C.E. Clayton | R. Yoder | K.A. Marsh1 | J.B. Rosenzweig | C. Pellegrini | and C. Joshi11
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.
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title: Results of the VISA SASE FEL Experiment at 840 nm
format: conference proceeding
conference: FEL 2002 24th
year: 2003
26 authors: A. Murokh | R. Agustsson | M. BABZIEN | I. Ben-Zvi | L. Bertolini | K. van Bibber | R. Carr | M. Cornacchia | P. Frigola | J. Hill | E. Johnson | L. Klaisner | G.P. Le Sage | M. Libkind | R. Malone | H-D. Nuhn | C. Pellegrini | Sven Reiche | G. Rakowsky | J.B. Rosenzweig | Ruland, R. | Skaritka, J. | A. Toor | A. Tremaine | X. Wang | V. Yakimenko
abstract: VISA (Visible to Infrared SASE Amplifier) is a high-gain self-amplified spontaneous emission (SASE) free-electron laser (FEL), which achieved saturation at 840 nm within a single-pass 4-m undulator. A gain length shorter than 18 cm has been obtained, yielding the gain of 2x10(8) at saturation. The FEL performance, including the spectral, angular, and statistical properties of SASE radiation, has been characterized for different electron beam conditions. The results are compared to 3-D SASE FEL theory and start-to-end numerical simulations of the entire injector, transport, and FEL system. Detailed agreement between simulations and experimental results is obtained over the wide range of the electron beam parameters.
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title: Measurements of nonlinear harmonic radiation and harmonic microbunching in a visible SASE FEL
format: conference proceeding
conference: FEL 2002 24th
year: 2003
13 authors: A. Tremaine | X. J. Wang | M. Babzien | I. Ben-Zvi | M. Cornacchia | R. Malone | A. Murokh | H. D. Nuhn | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | Skaritka, J. | 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.
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title: Pulse length control in an X-ray FEL by using wakefields
format: conference proceeding
conference: FEL 2002 24th
year: 2003
3 authors: Sven Reiche | P. Emma | C. Pellegrini
abstract: For the users of the high-brightness radiation sources of free-electron lasers it is desirable 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 longitudinal wakefields in the undulator 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.
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title: Fundamental and Harmonic Microbunching Measurements in a High-Gain, Self-Amplified, Spontaneous Emission Free-Electron Laser
format: preprint
year: 2002
13 authors: A. Tremaine | X. J. Wang | M. Babzien | I. Ben-Zvi | M. Cornacchia | A. Murokh | H. D. Nuhn | R. Malone | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | Skaritka, J. | 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.
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title: Fundamental and harmonic microbunching in a high-gain self-amplified spontaneous-emission free-electron laser
format: journal article
publisher: Physical Review E
year: 2002
13 authors: A. Tremaine | X.J. Wang | M. Babzien | I. Ben-Zvi | M. Cornacchia | A. Murokh | H. D. Nuhn | R. Malone | C. Pellegrini | Sven Reiche | J.B. 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.
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title: Inverse Free Electron Laser Experiment at the Neptune Laboratory
format: conference proceeding
conference: AAC 2002 10th
year: 2002
6 authors: P. Musumeci | C. Pellegrini | J.B. Rosenzweig | A. A. Varfolomeev | Tolmachev, S. | 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
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title: Chirped-beam two-stage free-electron laser for high-power femtosecond x-ray pulse generation
format: journal article
publisher: Journal of the Optical Society of America B-Optical Physics
year: 2002
5 authors: C. B. Schroeder | C. Pellegrini | Sven 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.
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title: Bunched Beam Injection in a Plasma Accelerator
format: conference proceeding
conference: AAC 2002 10th
year: 2002
6 authors: S. Ya. Tochitsky | P. Musumeci | C. E. Clayton | C. Pellegrini | J.B. Rosenzweig | C. Joshi
abstract: An experiment on phase-locked injection of ~ 100 fs electron bunches in a plasma beat wave accelerator is presented. We consider using an IFEL microbunching technique to produce ultrashort electron bunches prebunched at the exact wavelength of the plasma wave 340 Jim (~lTHz). It is proposed to generate 100 MW of 1 THz radiation by difference frequency generation in a nonlinear crystal, mixing the same two CC>2 lines as used to drive the plasma accelerator.
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title: Properties of an Ultra-Short Gain Length, Saturated, Self-Amplified Spontaneous Emission FEL
format: preprint
year: 2002
26 authors: A. Murokh | R. Agustsson | Pedro Frigola | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | A. Tremaine | M. Babzien | I. Ben-Zvi | E. Johnson | R. Malone | G. Rakowsky | Skaritka, J. | X. Wang | V. Yakimenko | L. Bertolini | J. M. Hill | G.P. Le Sage | M. Libkind | A. Toor | K. A. Van Bibber | R. Carr | M. Cornacchia | L. Klaisner | H. D. Nuhn | Ruland, R.
abstract: The VISA experiment, conducted at the BNL Accelerator Test Facility (ATF), has studied the properties of SASE FEL process in a saturating system. The experiment utilized a high brightness electron beam and a strong focusing undulator. Saturated gain greater than 108, with a power gain length below 18 cm, was obtained at 840 nm. Measurements of FEL gain, spectral and angular properties of SASE radiation are reported, and the results are compared to theory and to start-to-end simulations of the system. FEL performance was found critically dependent on the compression of the electron beam.
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title: Experimental characterization of nonlinear harmonic radiation from a visible self-amplified spontaneous emission free-electron laser at saturation
format: journal article
publisher: Physical Review Letters
year: 2002
12 authors: A. Tremaine | X.J. Wang | M. Babzien | I. Ben-Zvi | M. Cornacchia | H. D. Nuhn | R. Malone | A. Murokh | C. Pellegrini | Sven Reiche | J.B. 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).
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title: Two-Stage Chirped-Beam SASE-FEL for High Power Femtosecond X-Ray Pulse Generation
format: preprint
year: December 10, 2001
5 authors: C. Schroeder | J. Arthur | P. Emma | Sven Reiche | C. Pellegrini
abstract:
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title: A THz radiation driven IFEL as a phaselocked prebuncher for a plasma beat-wave accelerator
format: conference proceeding
conference: International Conference on Lasers 2001
year: 2002
6 authors: P. Musumeci | S. Ya. Tochitsky | C. E. Clayton | C. Joshi | C. Pellegrini | J.B. 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.
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title: Characterization of an 800 nm SASE FEL at saturation
format: conference proceeding
conference: FEL 2001 23rd
year: 2002
24 authors: A. Tremaine | Pedro Frigola | A. Murokh | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | M. Babzien | I. Ben-Zvi | E. Johnson | R. Malone | G. Rakowsky | Skaritka, J. | X. J. Wang | K. A. Van Bibber | L. Bertolini | J. M. Hill | G.P. Le Sage | M. Libkind | A. Toor | R. Carr | M. Cornacchia | L. Klaisner | H. D. Nuhn | Ruland, R.
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).
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title: Chirped-beam two-stage SASE-FEL for high power femtosecond X-ray pulse generation
format: conference proceeding
conference: FEL 2001 23rd
year: 2002
5 authors: C. B. Schroeder | C. Pellegrini | Sven 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.
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title: An undulator with nonadiabatic tapering for the IFEL project
format: conference proceeding
conference: FEL 2001 23rd
year: 2002
6 authors: A. A. Varfolomeev | S.V. Tolmachev | T. V. Yarovoi | P. Musumeci | C. Pellegrini | J.B. 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.
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title: Start-to-end simulation for the LCLS X-ray FEL
format: conference proceeding
conference: FEL 2001 23rd
year: 2002
5 authors: S. Reiche | C. Pellegrini | J.B. Rosenzweig | P. Emma | P. Krejcik
abstract: X-ray FELs, such as the LCLS and TESLA FEL, require electron beams with large peak current and very small emittance. The X-ray peak power, temporal and spectral properties, depend significantly on details of the electron beam phase space distribution. The electron beam distribution is determined by many effects, as the emission process at the gun photo-cathode, bunch compression, acceleration and wakefields within the undulator. Although analytical results can give an estimate of the expected performance, the complexity of the electron beam generation, acceleration and compression can only be evaluated using a numerical simulation of all these processes, a start-to-end simulation. In this presentation we discuss the LCLS X-Ray FEL performance estimated by a start-to-end simulation, and we compare the results with those obtained using a simpler model. (20 References).
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title: Quantum effects in high-gain free-electron lasers
format: journal article
publisher: Physical Review E
year: 2001
3 authors: C.B. Schroeder | C. Pellegrini | P. Chen
abstract: A many-particle fully quantized theory for a free-electron laser which is valid in the high-gain regime is presented. We examine quantum corrections for the high-gain single-pass free-electron laser. It is shown that quantum effects become significant when the photon energy becomes comparable to the gain bandwidth. The initiation of the free-electron laser process from quantum fluctuations in the position and momentum of the electrons is considered, and the parameter regime for enhanced start-up is identified. Photon statistics of the free-electron laser radiation are discussed, and the photon number statistics for the self-amplified spontaneous emission are calculated. (21 References).
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title: Measuring FEL radiation properties at VISA-FEL
format: conference proceeding
conference: PAC 2001
year: 2001
25 authors: A. Murokh | R. Agustsson | Pedro Frigola | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | A. Tremaine | M. Babzien | I. Ben-Zvi | E. Johnson | R. Malone | G. Rakowsky | Skaritka, J. | X. J. Wang | K. A. Van Bibber | L. Bertolini | J. M. Hill | G.P. Le Sage | M. Libkind | A. Toor | R. Carr | M. Cornacchia | L. Klaisner | H. D. Nuhn | Ruland, R.
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).
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title: The free-electron laser collective instability and the development of X-ray FELs
format: conference proceeding
conference: PAC 2001
year: 2001
1 author: C. Pellegrini
abstract: We discuss the physics of collective instabilities in particle beams, and consider one particular case: the free-electron laser (FEL) collective instability. We present a review of the main characteristics of this instability, and its application to the development of Self Amplified Spontaneous Emission (SASE) FELs from the infrared to the X-ray region. (17 References).
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title: Start-to-end simulation for the LCLS X-ray FEL
format: conference proceeding
conference: PAC 2001
year: 2001
5 authors: Sven Reiche | C. Pellegrini | J.B. Rosenzweig | P. Emma | P. Krejcik
abstract: X-ray FELs, such as the LCLS and TESLA FEL, require electron beams with large peak current and very small emittance. The X-ray peak power, temporal and spectral properties, depend significantly on details of the electron beam phase space distribution. The electron beam distribution is determined by many effects, as the emission process at the gun photo-cathode, bunch compression, acceleration and wakefields within the undulator. Although analytical results can give an estimate of the expected performance, the complexity of the electron beam generation, acceleration and compression can only be evaluated using a numerical simulation of all these processes, a start-to-end simulation. In this presentation we discuss the LCLS X-Ray FEL performance estimated by a start-to-end simulation, and we compare the results with those obtained using a simpler model. (19 References).
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title: On the IFEL experiment at the UCLA Neptune Lab
format: conference proceeding
conference: PAC 2001
year: 2001
6 authors: P. Musumeci | C. Pellegrini | J.B. Rosenzweig | A. A. Varfolomeev | Tolmachev, S. | T. Yarovoi
abstract: We present an inverse free electron laser accelerator proposed for construction at the UCLA Neptune Lab. This experiment will use a 1TW CO/sub 2/ laser to accelerate through two strongly tapered undulators an electron beam from 16 MeV up to 55 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 Guoy phase shift. Ponderomotive effects and implications for tolerances are also studied. (13 References).
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title: Saturation measurements of a visible SASE FEL
format: conference proceeding
conference: PAC 2001
year: 2001
14 authors: A. Tremaine | P. Frigola | A. Murokh | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | M. Babzien | I. Ben-Zvi | E. Johnson | R. Malone | G. Rakowsky | Skaritka, J. | X. J. Wang | V. Yakimenko
abstract: VISA (visible to infrared SASE amplifier) is an FEL designed to obtain high gain at a radiation wavelength of 800 nm. Large gain is achieved by driving the FEL with the 71 MeV, high brightness beam of the Accelerator Test Facility (ATF) and using a novel, strong focusing, 4 m long undulator with a gap of 6 mm and a period of 1.8 cm. We report measurements of exponential gain, saturation, and spectra of the FEL radiation intensity. (11 References).
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title: Chirped-beam two-stage SASE-FEL for high power femtosecond x-ray pulse generation
format: conference proceeding
conference: Conference on Optics for Fourth-Generation X-Ray Sources
year: 2001
5 authors: C. B. Schroeder | C. Pellegrini | Sven 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).
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title: Chirped-beam two-stage SASE-FEL for high power femtosecond X-ray pulse generation
format: conference proceeding
conference: PAC 2001
year: 2001
5 authors: C.B. 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 for the Linac Coherent Light Source (LCLS).
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title: Visible-infrared self-amplified spontaneous emission amplifier free electron laser undulator
format: journal article
publisher: Physical Review Special Topics-Accelerators & Beams
year: 2001
17 authors: R. Carr | M. Cornacchia | P. Emma | H. D. Nuhn | B. Poling | R. Ruland | E. Johnson | G. Rakowsky | J. Skaritka | S. Lidia | P. Duffy | M. Libkind | Pedro Frigola | A. Murokh | C. Pellegrini | J.B. Rosenzweig | A. Tremaine
abstract: The visible-infrared self-amplified spontaneous emission amplifier (VISA) free electron laser (FEL) is an experimental device designed to show self-amplified spontaneous emission (SASE) to saturation in the near infrared to visible light energy range. It generates a resonant wavelength output from 800?600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is designed to show how SASE FEL theory corresponds with experiment in this wavelength range, using an electron beam with emittance close to that planned for the future Linear Coherent Light Source at SLAC. VISA comprises a 4 m pure permanent magnet undulator with four 99 cm segments, each of 55 periods, 18 mm long. The undulator has distributed focusing built into it, to reduce the average beta function of the 70?85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walk-off, or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, we were able to control trajectory walk-off to less than
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title: Beam collimation for LCLS beam emittance and charge control
format: conference proceeding
conference: ICFA Beam Dynamics Workshop on Physics of, and Science with, the X-Ray Free-Electron Laser 19th
year: 2001
3 authors: C.B. Schroeder | H. D. 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).
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title: Initial gain measurements of an 800 nm SASE FEL, VISA
format: conference proceeding
conference: FEL 2000 22nd
year: 2001
26 authors: P. Frigola | A. Murokh | P. Musumeci | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | A. Tremaine | M. Babzien | I. Ben-Zvi | E. Johnson | R. Malone | G. Rakowsky | Skaritka, J. | X. J. Wang | K. A. Van Bibber | L. Bertolini | J. M. Hill | G.P. Le Sage | M. Libkind | A. Toor | R. Carr | M. Cornacchia | L. Klaisner | H. D. Nuhn | Ruland, R. | D. C. 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).
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title: Design considerations for a SASE X-ray FEL
format: conference proceeding
conference: FEL 2000 22nd
year: 2001
1 author: 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).
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title: Optimization of an x-ray SASE-FEL
format: conference proceeding
conference: FEL 2000 22nd
year: 2001
7 authors: C. Pellegrini | Sven Reiche | J.B. Rosenzweig | C. Schroeder | A. A. Varfolomeev | Tolmachev, S. | H. D. Nuhn
abstract: The most important characteristics of an X-ray SASE-FEL are determined by the electron beam energy, transverse and longitudinal emittance, and by choice of the undulator period, field, and gap. Among them are the gain and saturation length, the amount and spectral characteristics of the spontaneous radiation, the wake fields due to the vacuum pipe. The spontaneous radiation intensity is very large in all X-ray SASE-FELs now being designed, and it contributes to the final electron beam energy spread, thus affecting the gain. It also produces a large background for the beam and radiation diagnostics instrumentation. The wake fields due to the resistivity and roughness of the beam pipe through the undulator, also affects the beam 6-dimensional phase space volume, and thus the gain and the line width. In this paper, we discuss ways to optimize the FEL when considering all these effects. In particular we consider and discuss the use of a hybrid iron-permanent magnet helical undulator to minimize some of these effects, and thus optimize the FEL design.
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title: IFEL experiment at the Neptune Lab
format: conference proceeding
conference: AAC 2000 9th
year: 2001
2 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).
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title: Intra-undulator measurements at VISA FEL
format: conference proceeding
conference: FEL 2000 22nd
year: 2001
11 authors: A. Murokh | P. Frigola | C. Pellegrini | J.B. Rosenzweig | A. Tremaine | E. Johnson | X.J. Wang | V. Yakimenko | L. Klaisner | H-D. 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.
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title: Optimization of an X-ray SASE FEL
format: conference proceeding
conference: ICFA Beam Dynamics Workshop on Physics of, and Science with, the X-Ray Free-Electron Laser 19th
year: 2001
7 authors: C. Pellegrini | Sven Reiche | J.B. Rosenzweig | C. Schroeder | A. A. Varfolomeev | Tolmachev, S. | H-D. Nuhn
abstract: The most important characteristics of an X-ray SASE-FEL are determined by the electron beam energy, transverse and longitudinal emittance, and by choice of the undulator period, field, and gap. Among them are the gain and saturation length, the amount and spectral characteristics of the spontaneous radiation, the wake fields due to the vacuum pipe. The spontaneous radiation intensity is very large in all X-ray SASE-FELs now being designed, and it contributes to the final electron beam energy spread, thus affecting the gain. It also produces a large background for the beam and radiation diagnostics instrumentation. The wake fields due to the resistivity and roughness of the beam pipe through the undulator, also affects the beam 6-dimensional phase space volume, and thus the gain and the line width. In this paper, we discuss ways to optimize the FEL when considering all these effects. In particular we consider and discuss the use of a hybrid iron-permanent magnet helical undulator to minimize some of these effects, and thus optimize the FEL design.
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title: Initial operation of S-band plane wave transformer photoinjector
format: conference proceeding
conference: APS April Meeting
year: 2000
4 authors: X. Ding | C. Pellegrini | J.B. 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.
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title: Commissioning of the Neptune Photoinjector
format: conference proceeding
conference: APS April Meeting
year: 2000
13 authors: S. Anderson | J.B. Rosenzweig | Burke, A. | X. Ding | Loh, M. | P. Musumeci | C. Pellegrini | Suk, H. | M.C. Thompson | C. Clayton | C. Joshi | Marsh, K. | 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.
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title: Boiling the Vacuum with an X-ray FEL
format: conference proceeding
conference: APS April Meeting
year: 2000
1 author: 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.
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title: Radiation pulse line-width and time duration control for an X-ray free-electron laser.
format: conference proceeding
conference: APS April Meeting
year: 2000
1 author: C. Pellegrini
abstract: An X-ray free-electron laser, named the Linear Coherent Light Source (LCLS), will be built at SLAC using the SLAC linear accelerator. LCLS is being developed by a SLAC-ANL-BNL-LANL-UCLA collaboration. The LCLS will produce coherent radiation at 1.5 to 0.15 nm, with peak power as high as 10 GW in a 100fs pulse length, and a line width of about 0.01possibilities now being studied to manipulate the X-ray pulse to control the peak power between 1 and 10 GW, the line-width between 0.01between 100 and 10 fs.
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title: Plasma source test and simulation results for the underdense plasma lens experiment at the UCLA Neptune Laboratory
format: journal article
publisher: IEEE Transactions on Plasma Science
year: 2000
8 authors: H. Suk | C. E. Clayton | C. Joshi | T.C. Katsouleas | P. Muggli | R. Narang | C. Pellegrini | J.B. Rosenzweig
abstract: The planned plasma lens experiment at the UCLA Neptune Laboratory is described. In the experiment, electron beams with an energy of 16 MeV, a charge of 4 nC, and a pulse duration of 30 ps full-width at half-maximum (FWHM) are designed to be produced from the 1.625-cell photoinjector radio-frequency gun (f=2.856 GHz) and PWT linac in the Neptune. The generated beams are passed through a thin plasma with a density of low 10/sup 12/ cm/sup -3/ range and a thickness of a few centimeters. For this experiment, a LaB/sub 6/-based discharge plasma source was developed and tested. In this paper, the overview of the planned plasma lens experiment and the test results of the plasma source for various conditions are presented. In addition, computer simulations with a 2-1/2 dimensional particle-in-cell code (MAGIC) were performed and the simulation results are shown. (19 References).
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title: IFEL experiment at Neptune Lab
format: conference proceeding
conference: EPAC 2000
year: 2000
2 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.
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title: A two stage IFEL accelerator
format: conference proceeding
conference: APS April Meeting
year: 2000
2 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.
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title: Report of the U.S. Department of Energy Fusion Energy Sciences Advisory Committee (FESAC) panel reviewing the theory and computing program
format: journal article
publisher: Journal of Fusion Energy
year: 2000
16 authors: J. Sheffield | T. M. Antonsen | L. A. Berry | M. R. Brown | J. P. Dahlburg | R. C. Davidson | M. Greenwald | C. C. Hegna | W. McCurdy | D. E. Newman | C. Pellegrini | C. K. Phillips | D. E. Post | M. N. Rosenbluth | T. C. Simonen | J. Van Dam
abstract: This Panel was set up by the Fusion Energy Sciences Advisory Committee (FESAC) at its November 2000 meeting for the purpose of addressing questions from the Department of Energy concerning the theory and computing/simulation program of the Office of Fusion Energy Sciences. Although the Panel primarily addressed programmatic questions, it acknowledges that the theory and computing in fusion energy sciences has a stellar record of research successes. (A recent FESAC report entitled "Opportunities in the Fusion Energy Sciences Program" listed a number of theory and computing research highlights.) Last year the National Research Council performed an assessment of the quality of the fusion energy sciences program-including theory and computing-and concluded that the quality of its research is on a par with that of other leading areas of contemporary physical science.
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title: High power femtosecond pulses from an X-ray SASE-FEL
format: conference proceeding
conference: FEL 1999 21st
year: 2000
1 author: 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).
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title: Status and initial commissioning of a high gain 800 nm SASE FEL
format: conference proceeding
conference: FEL 1999 21st
year: 2000
22 authors: A. Tremaine | Pedro Frigola | A. Murokh | P. Musumeci | C. Pellegrini | J.B. Rosenzweig | M. Babzien | Ben-Zvi, I. | E. Johnson | R. Malone | G. Rakowsky | Skaritka, J. | X.J. Wang | Yu, L. H. | Van Bibber, K. A. | J.M. Hill | G.P. Le Sage | R. Carr | M. Cornacchia | Nuhn, H. D. | Ruland, R. | D. C. Nguyen
abstract: We describe the status and initial commissioning of the visible to infrared SASE amplifier (VISA) experiment. VISA uses a strong focusing 4 m undulator, the Brookhaven National Laboratory ATF linac with an energy of 72 MeV, and a photoinjector electron source. The VISA fundamental radiation wavelength is near 800 nm and the power expected at saturation is near 60 MW. Power, angular and spectral measurements are planned for the VISA radiation and these results will be analyzed and compared with SASE FEL theory and computer simulation. In addition, the induced electron beam micro-bunching will be measured using coherent transition radiation. (12 References).
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title: The development of S-band plane wave transformer photoinjector
format: conference proceeding
conference: PAC 1999
year: 1999
11 authors: X. Ding | C. Pellegrini | J.B. Rosenzweig | S. Telfer | A. Tremaine | Vernon, W. | D. Yu | D. Newsham | Zeng, J. | Lee, T. | Chen, J.
abstract: An integrated S-band RF photoinjector based on the plane wave transformer (PWT) is being built in the Particle Beam Physics Laboratory at UCLA in collaboration with DULY Research. 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 20 MeV, with emittance less than 1 mm-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 SASEFEL physics studies. It will also provide commercial opportunities in chemistry, biology and medicine. The present status of the PWT photoinjector including fabrication and cold test to characterise the structure is described. RF system and photocathode drive laser system are also discussed.
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title: Commissioning of the Neptune photoinjector
format: conference proceeding
conference: PAC 1999
year: 1999
21 authors: S. Boucher | P. Musumeci | Loh, M. | Burke, A. | S. Anderson | J.B. Rosenzweig | K. Bishofberger | X. Ding | Holden, T. | A. Murokh | C. Pellegrini | Suk, H. | A. Tremaine | C. Clayton | C. Joshi | Marsh, K. | P. Muggli | M.C. Thompson | S. Anderson | R. Agustsson | R. 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).
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title: Underdense plasma lens experiment at the UCLA Neptune Laboratory
format: conference proceeding
conference: PAC 1999
year: 1999
10 authors: Suk, H. | C. E. Clayton | G. Hairapetian | C. Joshi | Loh, M. | P. Muggli | R. Narang | C. Pellegrini | J.B. Rosenzweig | T.C. Katsouleas
abstract: An underdense plasma-lens experiment is planned at the UCLA Neptune Laboratory. For this experiment, a LaB/sub 6/-based discharge plasma source was developed and tested. Test results of the plasma source show that it can provide satisfactory Ar plasma parameters for underdense plasma lens experiments, i.e., a density in the low 10/sup 12/ cm/sup -3/ range and a thickness of a few cm. In the plasma chamber a YAG slab and a Cherenkov radiator are placed for electron beam diagnostics so that both time-integrated and time-resolved information will be obtained and compared with the MAGIC code (2 and 1/2 dimensional particle-in-cell) simulations. In this paper, the planned experiment including test results of the plasma source, diagnostics and MAGIC simulation results is presented. (5 References).
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title: Optimal scaled photoinjector designs for FEL applications
format: conference proceeding
conference: PAC 1999
year: 1999
5 authors: J.B. Rosenzweig | S. Anderson | X. Ding | C. Pellegrini | G. Travish
abstract: Much of the research and development surrounding the effort to create X-ray FELs based on the SASE process has centered on the creation of ultra-high brightness electron beam sources. The sources for existing short wavelength FEL designs, which employ RF photoinjector technology, have all been specified to contain 1 nC of charge. We show, by scaling existing designs, that this constraint causes the maximum beam brightness to be found when the RF wavelength is shortened to X-band. If, instead of holding the charge constant, we assume a certain RF wavelength device and then scale the charge, notable improvements in the beam brightness, and thus the FEL performance, are found. Charge scaling assumes that the density and aspect ratio of the beam stays constant as the charge is changed. If we relax the requirement of a constant aspect ratio in order to maximize the beam current and brightness by shortening the beam pulse, we find that the pulse lengthening due to space charge eventually brings this effort to a stop. The results of this investigation and their impact on SASE FEL design is discussed.
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title: A measurement of high gain SASE FEL induced electron beam micro-bunching using coherent transition radiation
format: conference proceeding
conference: PAC 1999
year: 1999
9 authors: A. Tremaine | S. Anderson | Pedro Frigola | M. Hogan | A. Murokh | C. Pellegrini | J.B. Rosenzweig | D. Nguyen | Sheffield, R.
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).
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title: Photon beam diagnostics for VISA FEL
format: conference proceeding
conference: PAC 1999
year: 1999
17 authors: A. Murokh | C. Pellegrini | J.B. Rosenzweig | Pedro Frigola | P. Musumeci | A. Tremaine | M. Babzien | Ben-Zvi, I. | A. Doyuran | E. Johnson | Skaritka, J. | X.J. Wang | Van Bibber, K. A. | J.M. Hill | G.P. Le Sage | D. Nguyen | M. Cornacchia
abstract: The VISA (Visible to Infrared SASE Amplifier) project is designed to be a SASE-FEL driven to saturation in the sub-micron wavelength region. Its goal is to test various aspects of the existing theory of self-amplified spontaneous emission, as well as numerical codes. Measurements include: angular and spectral distribution of the FEL light at the exit and inside of the undulator; electron beam micro-bunching using CTR; single-shot time resolved measurements of the pulse profile, using an auto-correlation technique and FROG algorithm. The diagnostics are designed to provide maximum information on the physics of the SASE-FEL process, to ensure a close comparison of the experimental results with theory and simulations. (9 References).
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title: Output power control in an X-ray FEL
format: conference proceeding
conference: PAC 1999
year: 1999
3 authors: C. Pellegrini | X. Ding | J.B. Rosenzweig
abstract: Recent theoretical and experimental advances of the high gain self-amplified spontaneous emission free-electron laser (SASE-FEL), have demonstrated the feasibility of using this system as a 4/sup th/ generation light source. This source will produce diffraction-limited radiation in the 0.1 nm region of the spectrum, with peak power of tens of GW, subpicosecond pulse length, and very large brightness. The peak power density in such a system is very large, and in some experiments it might damage the optical systems or the samples, or it might be simply larger than what is needed for the particular experiment being considered. Some options to reduce the power level, for example by using a gas absorption cell to reduce the X-ray intensity, have been studied. In this paper we discuss another possibility to control the power output of an X-ray SASE-FEL by varying the charge from the electron source, and the longitudinal bunch compression during the acceleration in the linac.
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title: Test results of the plasma source for underdense plasma lens experiments at the UCLA Neptune Lab
format: conference proceeding
conference: AAC 1998 8th
year: 1999
7 authors: Suk, H. | C. E. Clayton | R. Narang | P. Muggli | J.B. Rosenzweig | C. Pellegrini | C. Joshi
abstract: A plasma source was developed at UCLA for planned underdense plasma lens experiments, where the plasma density is less than the electron beam density. The argon plasma, produced by a discharge between a LaB_6 cathode at 1330 degrees C and a tantalum anode, is confined by a solenoidal magnetic field and flows transversely across the electron beam path. Extensive test of the plasma source is under way for various conditions before it is assembled with the UCLA photocathode-based electron linac. In particular, different longitudinal (with respect to the electron beam) plasma profiles and effective plasma lengths can be obtained by adjusting the moveable sliding door between the plasma source and the transverse beamline. Test results of the plasma source are presented. (11 References).
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title: Measured free-electron laser microbunching using coherent transition radiation
format: conference proceeding
conference: FEL 1998 20th
year: 1999
9 authors: A. Tremaine | J.B. Rosenzweig | S. Anderson | Pedro Frigola | M. Hogan | A. Murokh | C. Pellegrini | D. Nguyen | Sheffield, R.
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).
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title: An X-ray transition radiation beam profile detector for the LCLS
format: conference proceeding
conference: ICFA Workshop on Nonlinear and Collective Phenomena in Beam Physics
year: 1999
2 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).
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title: Experimental non linear beam dynamics studies with a turn-by-turn phase space monitor at SPEAR
format: conference proceeding
conference: ICFA Workshop on Nonlinear and Collective Phenomena in Beam Physics
year: 1999
3 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).
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title: The VISA FEL Undulator
format: conference proceeding
conference: FEL 1998 20th
year: 1999
14 authors: R. Carr | I. Ben-Zvi | L. Bertolini | M. Cornacchia | P. Emma | Pedro Frigola | E. Johnson | M. Libkind | S. Lidia | H. D. Nuhn | C. Pellegrini | G. Rakowsky | J.B. Rosenzweig | R. Ruland
abstract: The Visible-Infrared SASE Amplifier (VISA) FEL is an experimental device designed to show self amplified spontaneous emission (SASE) to saturation in the 800-600 nm range, where silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is the first SASE FEL designed to saturate, and its diagnostics will provide important checks of theory.
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title: Measurements of gain larger than 10(5) at 12 mu m in a self-amplified spontaneous-emission free-electron laser
format: journal article
publisher: Physical Review Letters
year: 1998
13 authors: M. Hogan | C. Pellegrini | J.B. Rosenzweig | S. Anderson | Pedro Frigola | A. Tremaine | C. Fortgang | D. C. Nguyen | R. L. Sheffield | J. Kinross-Wright | A. 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).
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title: Is the X-ray FEL the 4th generation light source?
format: conference proceeding
conference: EPAC 1998
year: 1998
1 author: 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.
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title: Measurements of High Gain and Intensity Fluctuations in a Self-Amplified, Spontaneous-Emission Free-Electron Laser
format: journal article
publisher: Physical Review Letters
year: 1998
12 authors: M. Hogan | C. Pellegrini | J.B. Rosenzweig | G. Travish | A. A. Varfolomeev | S. Anderson | K. Bishofberger | Pedro Frigola | A. Murokh | N. Osmanov | Sven 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.
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title: Coherent and Collective States in Beam-Radiation Interaction
format: journal article
publisher:
year: 1998
1 author: 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.
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title: Observations, Measurements and Applications of a Steady Collective Mode in an Electron Storage Ring
format: preprint
year: 1998
3 authors: A. Terebilo | C. Pellegrini | M. Cornacchia
abstract: A single bunch of charged particles in a storage ring is a system of 10(9) - 10(11) coupled non-linear oscillators with radiative energy loss and compensated by the accelerating cavity. A stable collective mode in such system was induced and observed in SPEAR storage rign using a turn-by-turn phase space monitor. New possibilities of using this mode as a tool to experimentally study non-linear dynamics in storage rings are discussed.
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title: Observation of Self-Amplified Spontaneous-Emission-Induced Electron-Beam Microbunching Using Coherent Transition Radiation
format: journal article
publisher: Physical Review Letters
year: 1998
9 authors: A. Tremaine | J.B. Rosenzweig | S. Anderson | Pedro Frigola | M. Hogan | A. Murokh | C. Pellegrini | D. C. Nguyen | R. L. Sheffield
abstract: We report the measurement of electron-beam microbunching at the exit of a self-amplified spontaneous-emission free-electron laser (SASE FEL), by observation of coherent transition radiation (CTR). The CTR was found to have an angular spectrum much narrower than spontaneous transition radiation and a narrow-band frequency spectrum. The central frequency of the fundamental CTR spectrum is found to differ slightly from that of the SASE, a finding in disagreement with previously invoked CTR theory. The CTR measurement establishes the uniformity of microbunching in the transverse dimension, indicating the SASE FEL operates in a dominant transverse mode.
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title: Emittance Studies of the BNL/SLAC/UCLA 1.6 Cell Photocathode RF Gun
format: conference proceeding
conference: PAC 1997
year: 1998
11 authors: D. T. Palmer | X. J. Wang | R. H. Miller | M. Babzien | I. Ben-Zvi | C. Pellegrini | Sheehan, J. | Skaritka, J. | 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).
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title: Beam dynamics in an integrated plane wave transformer photoinjector at S and X-band
format: conference proceeding
conference: PAC 1997
year: 1998
6 authors: J.B. Rosenzweig | X. Ding | D. T. 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).
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title: The Neptune photoinjector
format: conference proceeding
conference: ICFA Second Generation Plasma Acceleration Workshop
year: 1998
12 authors: J.B. Rosenzweig | S. Anderson | K. Bishofberger | X. Ding | A. Murokh | C. Pellegrini | Suk, H. | A. Tremaine | C. Clayton | C. Joshi | Marsh, K. | P. Muggli
abstract: The RF photoinjector in the Neptune advanced accelerator laboratory, along with associated beam diagnostics, transport and phase-space manipulation techniques are described. This versatile injector has been designed to produce short-pulse electron beams for a variety of uses: ultra-short bunches for injection into a next-generation plasma beatwave acceleration experiment, space-charge dominated beam physics studies, plasma wake-field acceleration driver, plasma lensing, and free-electron laser microbunching techniques. The component parts of the photoinjector, the RF gun, photocathode drive laser systems, booster linac, RF system, chicane compressor, beam diagnostic systems, and control system, are discussed. The present status of photoinjector commissioning at Neptune is reviewed, and proposed experiments are detailed. (33 References).
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title: The NEPTUNE facility for 2nd generation advanced accelerator experiments
format: conference proceeding
conference: PAC 1997
year: 1998
5 authors: C. E. Clayton | C. Joshi | K. A. Marsh | C. Pellegrini | J.B. Rosenzweig
abstract: The NEPTUNE Laboratory, under construction at UCLA, will be a user facility for exploring concepts useful for advanced accelerators. [1] The programmatic goal for the laboratory is to inject extremely high quality electron bunches into a laser-driven plasma beat wave accelerator (PBWA) [2] and explore ideas for extracting a high quality DE/E < 0.1, epsilon_n < 10 pi mm-mrad), high energy (100 MeV) beam from a plasma structure operating at about 1 THz and about 3 GeV/m. The lab will combine an upgraded MARS CO2 laser and the state-of-the-art SATURNUS RF gun and linac. [3] The new MARS laser will be about 1 TW (100 J, 100 ps), up from 0.2 TW (70 J, 350 ps). This allows for doubling the spot size at the IP and quadrupling the interaction length while still driving gradients of 3 GeV/m. The SATURNUS gun will be upgraded to the Brookhaven 1.6 cell design. [4] A novel, multi-cell Plane-Wave Transformer (PWT) RF gun is also under development. [5] A sync-pumped, sub-ps dye laser is available to directly produce ultrashort electron pulses (1/5 of an accelerating bucket). Part of the research program will be devoted to studying pulse compression [6] and phaselocking techniques at these ultrahigh frequencies and diagnosing microbunches generated by such structures. [7] Finally, shaped electron pulses will be studied for the electron driven Plasma Wakefield Accelerator (PWFA) concept.
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title: A plane-wave-transformer photoelectron linac
format: conference proceeding
conference: PAC 1997
year: 1998
7 authors: D. Yu | Lee, T. | Rajagopalan, S. | Chen, J. | C. Pellegrini | J.B. 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).
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title: Measurement of the variation of machine parameters and the effect of the power supplies ripple on the instantaneous tunes at SPEAR
format: conference proceeding
conference: PAC 1997
year: 1998
5 authors: A. Terebilo | C. Pellegrini | M. Cornacchia | Corbett, J. | Martin, D.
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).
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title: Experimental nonlinear beam dynamics studies at SPEAR
format: conference proceeding
conference: PAC 1997
year: 1998
5 authors: A. Terebilo | C. Pellegrini | M. Cornacchia | Corbett, J. | Martin, D.
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).
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title: UCLA-KIAE focusing permanent magnet undulator for SASE experiment
format: conference proceeding
conference: FEL 1997 19th
year: 1998
9 authors: Osmanov, N. | Tolmachev, S. | A. A. Varfolomeev | A. A. Varfolomeev | Pedro Frigola | M. Hogan | C. Pellegrini | R. Carr | Lidia, S.
abstract: A description of a new 2 m undulator is presented which was specially designed and manufactured for a SASE mode FEL experiment. It is a one section two plane focusing permanent magnet construction. The uniform period length is 2.06 cm, total number of periods is 98. The peak field on the axis is 5.4 kG for a 5 mm gap. (8 References).
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title: Second generation beatwave experiments at UCLA
format: conference proceeding
conference: ICFA Second Generation Plasma Acceleration Workshop
year: 1998
5 authors: C. E. Clayton | C. Joshi | K. A. Marsh | C. Pellegrini | J.B. Rosenzweig
abstract: The NEPTUNE laboratory, under construction at UCLA, will be a user facility for exploring concepts useful for advanced accelerators. The primary programmatic goal for the laboratory is to inject extremely high-quality electron bunches into a laser-driven plasma beat wave accelerator and explore ideas for extracting a high-quality Delta E/E<0.1, epsilon <10 pi mm mrad, high-energy (100 MeV) beam from a plasma structure operating at about 1 THz and about 3 GeV/m. The lab will combine an upgraded MARS CO_2 laser and the state-of-the-art SATURNUS RF gun and linac, also undergoing an upgrade. The new MARS laser will be about 1 TW (100 J, 100 ps), up from 0.2 TW (70 J, 350 ps). This allows for doubling the spot size of the laser beam and thereby quadrupling the interaction length while still driving gradients of 3 GeV/m. The large diameter of the accelerating structure relative to the injected electron bunches (10:1 ratio) will minimize the deleterious effects of the radial dependence of the accelerating field and soften the radial focusing thus permitting, in principle, the extraction of a high-quality accelerated beam.
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title: Measurements of high gain and noise fluctuations in a SASE free electron laser
format: conference proceeding
conference: FEL 1997 19th
year: 1998
12 authors: M. Hogan | S. Anderson | K. Bishofberger | P. Frigola | A. Murokh | N. Osmanov | C. Pellegrini | S. Reiche | J.B. Rosenzweig | G. Travish | A. Tremaine | A.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).
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title: Study of a novel compact standing wave RF linac
format: journal article
publisher: Nuclear Instruments & Methods in Physics Research
year: 1997
3 authors: R. Zhang | C. Pellegrini | R. Cooper
abstract: A novel, compact RF linac structure, the plane wave transformer (PWT), is studied. The PWT provides high accelerating field and high efficiency, and can be used to accelerate high-brightness beams. PWT linac prototypes with eight cells at S-band have been developed at UCLA and successfully used to accelerate an electron beam by more than 10 MeV in 40 cm. In this paper, we describe the principal properties of this structure, the electric parameters obtained from numerical simulation, and measurement results from microwave cold tests. The mechanical design for prototype linacs is also reported. (13 References).
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title: Measurements of high gain and noise fluctuations in a SASE free electron laser
format: conference proceeding
conference: Workshop on Single Pass, High Gain FELs Starting from Noise Aiming at Coherent X-Rays
year: 1997
12 authors: M. Hogan | S. Anderson | K. Bishofberger | Pedro Frigola | A. Murokh | N. Osmanov | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | G. Travish | A. Tremaine | A. 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).
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title: Experimental confirmation of transverse focusing and adiabatic damping in a standing wave linear accelerator
format: journal article
publisher: Physical Review E
year: 1997
10 authors: Sven Reiche | J.B. Rosenzweig | S. Anderson | Pedro 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.
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title: Generation of sub-picosecond electron bunches from RF photoinjectors
format: journal article
publisher: Nuclear Instruments & Methods in Physics Research
year: 1997
3 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).
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title: The UCLA high gain infrared free electron laser
format: conference proceeding
conference: FEL 1996 18th
year: 1997
5 authors: M. Hogan | C. Pellegrini | J.B. Rosenzweig | G. Travish | A. A. Varfolomeev
abstract: A high gain SASE FEL amplifier designed to operate in the infrared (near 10 mu m) is being commissioned in the particle beam physics laboratory at UCLA. The high brightness beam needed to drive the FEL is provided by an RF photocathode gun employing solenoidal emittance compensation. A novel linac (a plane wave transformer) accelerates the beam to a final energy [left angle bracket]or=15 MeV. This beam is to be sent through a 60 cm long undulator with a period of 1.5 cm and an undulator parameter K approximately=1. Near future experiments will focus on FEL physics relevant to proposed short wavelength devices. Investigations of start-up from noise (SASE), effects of beam parameters on gain as well as noise fluctuations are of particular interest. Here we present an overview of the hardware including relevant diagnostics, measured beam parameters, FEL simulation results and the status of proposed experiments. (9 References).
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title: Measurements of the tune variations induced by non-linearities in lepton machines
format: conference proceeding
conference: EPAC 1996
year: 1997
9 authors: Bartolini, R. | Giovannozzi, M. | Scandale, W. | Verdier, A. | C. Pellegrini | Tran, P. | Todesco, E. | Corbett, J. | 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).
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title: Initial commissioning results of the Next Generation Photoinjector
format: conference proceeding
conference: AAC 1997 7th
year: 1997
11 authors: D. T. Palmer | X.J. Wang | R. H. Miller | M. Babzien | Ben-Zvi, I. | C. Pellegrini | Sheehan, J. | Skaritka, J. | 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).
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title: Space-charge oscillations in a self-modulated electron beam in multi-undulator free-electron lasers
format: conference proceeding
conference: FEL 1996 18th
year: 1997
5 authors: J.B. Rosenzweig | C. Pellegrini | L. Serafini | C. Ternieden | G. Travish
abstract: We examine here the oscillation of electron-beam density perturbations (longitudinal plasma oscillations) produced at the exit of a high-gain free-electron laser (FEL) by the action of the FEL instability. These oscillations, which are analyzed in the case of both a free-space drift and a dispersive section, can degrade the bunching of the beam in the drift between undulator sections in multi-stage FELs. The impact of these oscillations on the gain of an FEL in an undulator following such a drift, as well as the case of an optical klystron is studied. (9 References).
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title: Status of UCLA IR FEL
format: preprint
year: 1996
21 authors: C. Pellegrini | G. Baranov | N. Barov | P. Davis | M. Fauver | B. Gitter | G. Hairapetian | S. Hartman | M. Hogan | S. Ivanchenkov | C. Joshi | A. Khlebnikov | P. Kwok | N. Luhmann | S. Park | J.B. Rosenzweig | K. Schenk | Smolin, J. A. | P. Tran | G. Travish | A. A. Varfolomeev
abstract:
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title: A plasma klystron for generating ultra-short electron bunches
format: conference proceeding
conference: Workshop on Second Generation Plasma Accelerators
year: 1996
7 authors: T.C. Katsouleas | C. E. Clayton | L. Serafini | C. Pellegrini | C. Joshi | Dawson, J. | Castellano, P.
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.
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title: Effects of undulator interruptions on the performance of high-gain FEL amplifiers
format: conference proceeding
conference: FEL 1995 17th
year: 1996
3 authors: K.J. Kim | Xie, M. | 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).
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title: Research and development toward a 4.5-1.5 angstrom linac coherent light source (LCLS) at SLAC
format: conference proceeding
conference: FEL 1995 17th
year: 1996
32 authors: R. Tatchyn | J. Arthur | M. Baltay | K. Bane | R. Boyce | M. Cornacchia | T. Cremer | A. Fisher | S. J. Hahn | M. Hernandez | G. Loew | R. Miller | W. R. Nelson | H. D. Nuhn | D. Palmer | J. Paterson | T. Raubenheimer | J. Weaver | H. Wiedemann | H. Winick | C. Pellegrini | G. Travish | E. T. Scharlemann | S. Caspi | W. Fawley | K. Halbach | K. J. Kim | R. Schlueter | M. Xie | D. Meyerhofer | R. Bonifacio | L. De Salvo
abstract: In recent years significant studies have been initiated on the feasibility of utilizing a portion of the 3 km S-band accelerator at SLAC to drive a short wavelength (4.5-1.5 Angstrom) Linac Coherent Light Source (LCLS), a Free-Electron Laser (FEL) operating in the Self-Amplified Spontaneous Emission (SASE) regime. Electron beam requirements for single-pass saturation in a minimal time include: 1) a peak current in the 7 kA range, 2) a relative energy spread of <0.05%, add 3) a transverse emittance, epsilon [rad-m], approximating the diffraction-limit condition epsilon=lambda/4 pi, where lambda[m] is the output wavelength. Requirements on the insertion device include field error levels of 0.02% for keeping the electron bunch centered on and in phase with the amplified photons, and a focusing beta of 8 m/rad for inhibiting the dilution of its transverse density. Although much progress has been made in developing individual components and beam-processing techniques necessary for LCLS operation down to similar to 20 Angstrom, a substantial amount of research and development is still required in a number of theoretical and experimental areas leading to the construction and operation of a 4.5-1.5 Angstrom LCLS. In this paper we report on a research and development program underway and in planning at SLAC for addressing critical questions in these areas. These include the construction and operation of a linac test stand for developing laser-driven photocathode rf guns with normalized emittances approaching 1 mm-mrad; development of advanced beam compression, stability, and emittance control techniques at multi-GeV energies; the construction and operation of a FEL Amplifier Test Experiment (FATE) for theoretical and experimental studies of SASE at IR wavelengths; an undulator development program to investigate superconducting, hybrid/permanent magnet (hybrid/PM), and pulsed-Cu technologies; theoretical and computational studies of high-gain FEL physics and LCLS component designs; development of X-ray optics and instrumentation for extracting, modulating, and delivering photons to experimental users; and the study and development of scientific experiments made possible by the source properties of the LCLS.
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title: Applications of short bunches
format: conference proceeding
conference: Micro Bunches Workshop
year: 1996
1 author: 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).
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title: Electron micro-bunch generation from RF photoinjectors
format: conference proceeding
conference: Micro Bunches Workshop
year: 1996
3 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).
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title: Measurements of the octupole-induced amplitude-dependent frequency shift in SPEAR
format: conference proceeding
conference: PAC 1995
year: 1995
5 authors: Tran, P. | C. Pellegrini | Yang, J. | M. Cornacchia | Corbett, J.
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).
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title: An injector-prebuncher for a plasma electron accelerator
format: conference proceeding
conference: PAC 1995
year: 1995
5 authors: M. Lampel | C. Pellegrini | R. Zhang | C. Joshi | W. M. 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).
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title: Status of the UCLA high-gain infrared free electron laser
format: conference proceeding
conference: PAC 1995
year: 1995
5 authors: M. Hogan | C. Pellegrini | J.B. Rosenzweig | G. Travish | A. A. Varfolomeev
abstract: A compact, infrared (10-20 mu m), high-gain FEL is being commissioned at the Particle Beam Physics Laboratory (PBPL) at UCLA. A 60 cm long undulator with a period of 1.5 cm and an undulator parameter K-l has been built to be used in conjunction with the PBPL beam. Experiments will focus on EEL physics pertinent to proposed short wavelength devices. Of particular interest is exploration of startup from noise, self amplified spontaneous emission (SASE), beam parameter effects on gain, and output power fluctuations. Beam micro-bunching due to the FEL action will also be measured using coherent transition radiation. Here we present an overview of the relevant diagnostics, FEL simulation results and proposed experiments. (13 References).
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title: Initial operation of the UCLA plane wave transformer (PWT) linac
format: conference proceeding
conference: PAC 1995
year: 1995
10 authors: R. Zhang | P. Davis | G. Hairapetian | M. Hogan | C. Joshi | M. Lampel | S. Park | C. Pellegrini | J.B. 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).
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title: The UCLA compact high brightness electron accelerator
format: conference proceeding
conference: PAC 1995
year: 1995
10 authors: P. Davis | G. Hairapetian | M. Hogan | C. Joshi | M. Lampel | S. Park | C. Pellegrini | J.B. Rosenzweig | G. Travish | R. Zhang
abstract: We report the characteristics and performance of the UCLA S-band compact electron accelerator, consisting of a high brightness, 8 cm long, photo-injector with a copper cathode, followed by a 42 cm long plane wave transformer accelerating structure, delivering a beam energy of 10 MeV. The photo-electrons are produced by a 266 nm laser pulse of less than 4 ps in duration. Over time the laser induced electron emission decreases and the emission from the cathode surface becomes structured. Measurements of the quantum efficiency for Cu before and after this degradation are presented along with images of the non uniform electron emission. (8 References).
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title: A proposed dielectric-loaded resonant laser accelerator
format: journal article
publisher: Physical Review Letters
year: 1995
3 authors: J.B. 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).
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title: Summary of Exotic Collider Concepts Group
format: conference proceeding
conference: AAC 1994 6th
year: 1995
1 author: C. Pellegrini
abstract: We present a summary of the discussions in the Exotic Collider Concepts Group. Most of the discussions were centered around the status and open problems for muon-muon and gamma-gamma colliders. In addition the group discussed some general problems and new results of accelerator physics.
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title: Transverse dynamics of a short, relativistic electron bunch in a plasma lens
format: conference proceeding
conference: Annual Meeting of the Division of Plasma Physics of the APS
year: 1995
6 authors: G. Hairapetian | P. Davis | C. E. Clayton | C. Joshi | C. Pellegrini | T. Katsouleas
abstract: Dynamic focusing of a 3.8 MeV, 25 ps long, full width at half-maximum (FWHM), electron bunch by an overdense (n/sub p/[right angle bracket][right angle bracket]n/sub b/, where n/sub p/ and n/sub b/ are the plasma and bunch densities, respectively) plasma lens has been studied experimentally. The plasma focused the bunch from an initial transverse size of approximately 2.4 mm (FWHM) to about 0.5 mm, 21 cm downstream of the plasma. The sharp rise time (7 ps 10%-90%) of the electron bunch, excites a large-amplitude ([left angle bracket]1 MeV/m) plasma wave (plasma wake field). The peak focusing force of the lens is partly (60%) due to the beam-generated, azimuthal magnetic field and partly (40%) due to the radial component of the electrostatic wake field. (29 References).
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title: The UCLA high gain infrared FEL
format: conference proceeding
conference: FEL 1994 16th
year: 1995
4 authors: G. Travish | M. Hogan | C. Pellegrini | J.B. Rosenzweig
abstract: The particle beam physics laboratory (PBPL) at UCLA is constructing a short period FEL which will operate in the high gain regime. The focus of the work has been the production of a high brightness electron beam suitable for short wavelength FELs. Once operational the FEL will be used to study phenomena of significance to short wavelength devices such as SASE and performance sensitivity to various beam parameters. Future studies may include the addition of a second undulator or amplification of an input source (CO/sub 2/ laser) to study saturation, superradiance, and optical guiding. (11 References).
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title: A dielectric-loaded resonant laser accelerator
format: conference proceeding
conference: AAC 1994 6th
year: 1995
3 authors: J.B. 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).
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title: Parametric study of an X-ray FEL
format: conference proceeding
conference: FEL 1994 16th
year: 1995
7 authors: G. Travish | W. M. Fawley | K. J. Kim | H. D. Nuhn | C. Pellegrini | H. Winick | M. Xie
abstract: An FEL utilizing a high energy, high current and low emittance beam to produce radiation shorter than 2 angstroms is investigated in this paper. This device is an extension of the previously proposed 40 AA Linac Coherent Light Source based on the Stanford linear accelerator. Here we investigate the performance characteristics and parameter sensitivities of this single pass, high gain FEL amplifier operating by self-amplified spontaneous emission (SASE). We begin by comparing various approaches to this short wavelength source and justify our choice of a helical undulator operating on the fundamental frequency. Numerical simulations as well as extensions of previous studies are used to show performance as a function of undulator parameters, startup noise, emittance, focusing, current and energy spread. Further studies and parameter modifications are proposed where needed.
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title: Nonlinear beam dynamics experimental program at SPEAR
format: conference proceeding
conference: Workshop on Nonlinear Dynamics in Particle Accelerators: Theory and Experiments
year: 1995
5 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).
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title: Focusing of a Relativistic Electron Beam by an Underdense Plasma Lens
format: preprint
year: 1994
5 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: ...
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title: 25 MeV Injector for the Plasma Beat Wave Accelerator
format: preprint
year: 1994
5 authors: C. Joshi | M. Lampel | S. Park | C. Pellegrini | R. Zhang
abstract:
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title: Parametric study of an X-ray FEL
format: preprint
year: 1994
7 authors: G. Travish | W. Fawley | K. J. Kim | H. D. Nuhn | C. Pellegrini | H. Winick | M. Xie
abstract: An FEL utilizing a high energy, high current and low emittance beam to produce radiation shorter than 2 AA is investigated in this paper. This device is an extension of the previously proposed 40 AA Linac Coherent Light Source based on the Stanford linear accelerator. Here we investigate the performance characteristics and parameter sensitivities of this single pass, high gain FEL amplifier operating by self-amplified spontaneous emission (SASE). We begin by comparing various approaches to this short wavelength source and justify our choice of a helical undulator operating on the fundamental frequency. Numerical simulations as well as extensions of previous studies are used to show performance as a function of undulator parameters, startup noise, emittance, focusing, current and energy spread. Further studies and parameter modifications are proposed where needed.
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title: Short wavelength FELs using the SLAC linac
format: journal article
publisher: presented at the Fourth European Particle Acclerator Conference (EPAC'94), London, England, June 27-Julyy 1, 1994
year: 1994
30 authors: J. Cobb | D. Prosnitz | V. Vylet | J. Seeman | P. Pianetta | P. Morton | H. D. Nuhn | K. Bane | R. Boyce | G. Loew | R. Miller | J. Paterson | D. Palmer | T. Raubenheimer | R. Tatchyn | H. Winick | A. D. Yeremian | C. Pellegrini | J.B. Rosenzweig | G. Travish | E. T. Scharlemann | W. M. Fawley | K. Halbach | K. J. Kim | R. Schlueter | Sessler, A. M. | M. Xie | R. Bonifacio | L. De Salvo | P. Pierini
abstract: We have studied the use of the SLAC linac to drive FELs at wavelengths down to a few angstroms. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy eelctron beam through a long undulator by Self-Amplified-Spontaneous-Emissin (SASE). About 10(13) photons per pulse can be produced in 100 fs pulses at a 120 Hz rate, corresponding to brightness levels of about 10(22) average and 10(32) peak. Peak power levels are tens of GW. Electron energies of 10-20 GeV are required. Signifcant imporvement of FEL performance seems possible using harmonic generation techniques according to results from numerical simulations.
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title: Prospects for high power linac coherent light source (LCLS) development in the 1000 angstrom-1 angstrom wavelength range
format: conference proceeding
conference: International Colloquium on X-Ray Lasers 4th
year: 1994
26 authors: R. Tatchyn | K. Bane | R. Boyce | G. Loew | R. Miller | H. D. Nuhn | D. Palmer | J. Paterson | T. Raubenheimer | J. Seeman | H. Winick | D. Yeremian | C. Pellegrini | J.B. Rosenzweig | G. Travish | D. Prosnitz | E. T. Scharlemann | S. Caspi | W. Fawley | K. Halbach | K. J. Kim | R. Schlueter | M. Xie | R. Bonifacio | L. De Salvo | P. Pierini
abstract: Electron bunch requirements for single-pass saturation of a free-electron laser (FEL) operating at full transverse coherence in the self-amplified spontaneous emission (SASE) mode include: 1) a high peak current, 2) a sufficiently low relative energy spread, and 3) a transverse emittance epsilon (r-m) satisfying the condition epsilon <= lambda /4 pi , where lambda (m) is the output wavelength of the FEL. In the insertion device that induces the coherent amplification, the prepared electron bunch must be kept on a trajectory sufficiently collinear with the amplified photons without significant dilution of its transverse density. In this paper we discuss a Linac coherent light source (LCLS) based on a high energy accelerator such as, e.g., the 3 km S-band structure at the Stanford Linear Accelerator Center (SLAC), followed by a long high-precision undulator with superimposed quadrupole (FODO) focusing, to fulfill the given requirements for SASE operation in the 1000 angstrom-1 angstrom range. The electron source for the linac, an RF gun with a laser-excited photocathode featuring a normalized emittance in the 1-3 mm-mrad range, a longitudinal bunch duration of the order of 3 ps, and approximately 10(-9) C/bunch, is a primary determinant of the required low transverse and longitudinal emittances. Acceleration of the injected bunch to energies in the 5-25 GeV range is used to reduce the relative longitudinal energy spread in the bunch, as well as to reduce the transverse emittance to values consistent with the cited wavelength regime. Two longitudinal compression stages are employed to increase the peak bunch current to the 2-5 kA levels required for sufficiently rapid saturation. The output radiation is delivered, via a grazing-incidence mirror bank, to optical instrumentation and a multi-user beam line system. Technological requirements for LCLS operation at 40 angstroms, 4.5 angstroms, and 1.5 angstroms are examined.
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title: Study of magnetic lattice for a quasi-isochronous ring
format: journal article
publisher: Particle Accelerators
year: 1994
4 authors: A. Amiry | C. Pellegrini | E. Forest | D. Robin
abstract: Quasi-isochronous rings (QIRs) have been considered for electron-positron colliders to obtain large luminosity with a small average beam current. This approach offers the advantage of minimizing vacuum and RF system problems, and multibunch instability effects. In this paper, we review the basic physics of a QIR, the condition for stable single-particle motion, and the dynamic aperture. The collider we discuss is a Phi( Phi ) factory with a single ring and beam energy of 510 MeV. This ring uses a very strong focusing of the electron and positron beams at the interaction point, i.e., a beta function in the millimeter range; and a momentum compaction variable over a large range, of -0.008 to +0.005, to control the bunch length. It has a luminosity of 10(33) cm(-2) s(-1), average current smaller than 1 A, and a perimeter of 32.7 meter. Its transverse chromaticities and second-order momentum compaction are set to zero by utilizing three families of the sextupoles. The QIR dynamic aperture is calculated using a new computer code, KRAKPOT, written explicitly for small rings.
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title: Experimental demonstration of dynamic focusing of a relativistic electron bunch by an overdense plasma lens
format: journal article
publisher: Physical Review Letters
year: 1994
7 authors: G. Hairapetian | P. Davis | C. E. Clayton | C. Joshi | S. C. 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).
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title: The UCLA high gain infrared FEL
format: preprint
year: 1994
4 authors: G. Travish | M. Hogan | C. Pellegrini | J.B. Rosenzweig
abstract:
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title: Spectrum, temporal structure, and fluctuations in a high-gain free-electron laser starting from noise
format: journal article
publisher: Physical Review Letters
year: 1994
5 authors: R. Bonifacio | L. De Salvo | P. Pierini | N. Piovella | C. Pellegrini
abstract: We study the time structure, the frequency composition, and the shot to shot fluctuations of the radiation emitted by a free-electron laser starting from shot noise in the electron beam longitudinal distribution, taking into account slippage and finite bunch length effects. We find a very different behavior when the bunch length, l/sub b/, is much longer than the cooperation length, l/sub c/, or of the order of a few l/sub c/. The field evolution is dominated by slippage effects in both cases, and shows the presence of superradiant spikes. (14 References).
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title: Time and frequency domain analysis of superradiant coherent synchrotron radiation in a waveguide free-electron laser
format: journal article
publisher: Physical Review Letters
year: 1994
6 authors: A. Gover | F. V. Hartemann | G.P. Le Sage | N. C. Luhmann | R.S. Zhang | C. Pellegrini
abstract: The coherent synchrotron radiation process in a waveguide is theoretically investigated. A single, short bunch propagating through a wiggler is considered. In a waveguide, two very distinct regimes are possible. At grazing, where the beam velocity matches the wave group velocity, the bunch emits a single, ultrashort chirped pulse whose duration is determined by the interaction bandwidth and the waveguide dispersion. Away from grazing, where slippage dominates, two distinct pulses are radiated at the Doppler upshifted and downshifted frequencies. Both the time and frequency domain expressions for the radiation characteristics are derived. (13 References).
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title: Report on a Visit by American Scientists to UNK Project at IHEP-Protvino
format: preprint
year: January 8, 1993
6 authors: M. Medinnis | C. Pellegrini | Schlein, P. | Sessler, A. M. | Taylor, C. | Reardon, P.
abstract: This document results from a visit to the Institute for High Energy Physics in Protvino, Russia, by a group of U.S. physicists during 13-15 July, 1992. The purpose of the trip, which was supported by the U.S. National Science Foundation, was to learn about the state of the UNK superconducting 3 TeV accelerator complex and also to understand the cost and magnitude of the task required to complete the machine. If completed, UNK could provide a unique High Energy Physics facility. First, a collider version could serve as an excellent Factory to study the decay of Beauty particles. Secondly, the 3 TeV proton beam may be the highest energy available for a fixed target physics program. Although the superconducting magnet design is mature and tests have been successful, severe budget cutbacks have brought the project to a virtual halt. A realistic goal for IHEP may be the expeditious completion of UNK-1, the 600 GeV booster ring, in parallel with the pursuit of international collaboration on fiscal, technical and management support for the 3 TeV project.
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title: Collective instabilities in accelerator and storage rings
format: conference proceeding
conference: Andrew Sessler Symposium on the Physics of Beams
year: 1996
1 author: 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.
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title: A millimeter wave FEL driven by a photocathode RF linac
format: conference proceeding
conference: FEL 1993 15th
year: 1994
11 authors: R. Zhang | C. Pellegrini | J.B. Rosenzweig | G. LeSage | F. Hartemann | D. McDermott | C. Joshi | N. Luhmann | P. Pierini | de Salvo, L. | Bonifacio, R.
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).
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title: A Study of Linewidth, Noise and Fluctuations in a FEL Operating in SASE
format: conference proceeding
conference: FEL 1993 15th
year: 1994
5 authors: Bonifacio, R. | De Salvo, L. | P. Pierini | Piovella, N. | 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.
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title: The SLAC soft X-ray high power FEL
format: conference proceeding
conference: FEL 1993 15th
year: 1994
23 authors: C. Pellegrini | J.B. Rosenzweig | G. Travish | K. Bane | R. Boyce | G. Loew | P. Morton | H. D. Nuhn | J. Paterson | P. Pianetta | T. Raubenheimer | J. Seeman | R. Tatchyn | V. Vylet | H. Winick | K. Halbach | K. J. Kim | M. Xie | D. Prosnitz | E. T. Scharlemann | R. Bonifacio | L. De Salvo | P. Pierini
abstract: We discuss the design and performance of a 2 to 4 nm FEL operating in self-amplified spontaneous emission (SASE), using a photoinjector to produce the electron beam, and the SLAC linac to accelerate it to an energy of about 7 GeV. Longitudinal bunch compression is used to increase the peak current to 2.5 kA, while reducing the bunch length to about 40 mu m. The FEL field gain length is about 6 m, and the saturation length is about 60 m. The saturated output power is about 10 GW, corresponding to about 10/sup 14/ photons in a single pulse in a bandwidth of about 0.1%, with a pulse duration of 0.16 ps. Length compression, emittance control, phase stability, FEL design criteria, and parameter tolerances are discussed. (15 References).
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title: Initial measurements of the UCLA RF photoinjector
format: conference proceeding
conference: Conference on High Intensity Electron Sources
year: 1994
14 authors: S. Hartman | M. Hogan | S. C. Hartman | N. Barov | C. Pellegrini | S. Park | J.B. Rosenzweig | G. Travish | R. Zhang | C. Clayton | P. Davis | M. Everett | C. Joshi | G. Hairapetian
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).
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title: Slippage, noise and superradiant effects in the UCLA FEL experiment
format: conference proceeding
conference: FEL 1993 15th
year: 1994
5 authors: R. Bonifacio | P. Pierini | C. Pellegrini | J.B. Rosenzweig | G. Travish
abstract: We present the results of numerical calculations of the effects of noise, slippage and superradiance in the UCLA infrared (IR) free electron laser (FEL). The experiment, which uses a high brightness electron beam produced by a photocathode RF gun and a 1.5 cm period planar undulator, compares the FEL evolution starting from noise to that starting from an input signal. Numerical studies indicate that we can observe saturation, optical guiding effects and a superradiant spike.
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title: Experimental demonstration of plasma lens focusing
format: conference proceeding
conference: PAC 1993
year: 1993
7 authors: G. Hairapetian | P. Davis | C. E. 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).
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title: Quantum efficiency measurements of a copper photocathode in an RF electron gun
format: conference proceeding
conference: PAC 1993
year: 1993
8 authors: P. Davis | G. Hairapetian | C. Clayton | C. Joshi | S. Hartman | S. Park | C. Pellegrini | J.B. Rosenzweig
abstract: A 4.5 MeV photocathode RF gun has been commissioned at UCLA. A photo-injector drive laser produces sub 2 ps pulses of UV ( lambda =266 nm) light with up to 200 mu J/pulse, and illuminates a copper cathode. The photoelectrons are accelerated to an energy of 3.5 MeV within the gun. The electron beam charge is measured as a function of laser energy using an integrating current transformer (ICT). We present measurements of quantum efficiency as a function of laser polarization for injection angles of 2 degrees and 70 degrees with respect to the cathode normal. At 70 degrees incidence a 50% enhancement in quantum efficiency (>10(-4)) is observed for p-polarized light over s-polarized light. (7 References).
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title: The plane wave transformer linac development at UCLA
format: conference proceeding
conference: PAC 1993
year: 1993
3 authors: R. Zhang | S. Hartman | C. Pellegrini
abstract: A plane wave transformer linac (PWT), offering advantages of high efficiency, compactness, fabrication simplicity and cost, is being developed at UCLA. The PWT prototype at UCLA is an 8-cell, pi -mode, S-band standing-wave linac. To fully understand its physical properties, numerical modeling of the PWT prototype has been carried out by using the 3-D code MAFIA. A microwave test-stand with a network analyzer has also been set up to test these properties. In this paper. We present the important physical features, such as mode structures, dispersion curves, wake field, from the computation and/or the experiment. The measurements show good agreement with the numerical computation. (7 References).
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title: An inverse free electron laser driven linear collider electron-positron B-factory
format: conference proceeding
conference: PAC 1993
year: 1993
3 authors: N. Barov | C. Pellegrini | Sandweiss, J.
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).
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title: Extended version of an S-band RF gun
format: conference proceeding
conference: PAC 1993
year: 1993
2 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).
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title: Initial operation and beam characteristics of the UCLA S-band RF photo-injector
format: conference proceeding
conference: PAC 1993
year: 1993
10 authors: C. Pellegrini | N. Barov | S. C. Hartman | S. Park | J.B. 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).
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title: Quasi-isochronous storage rings
format: journal article
publisher: Physical Review E
year: 1993
4 authors: D. Robin | E. Forest | C. Pellegrini | A. Amiry
abstract: A study is made of the single-particle dynamics of an electron-positron storage ring where the phase-slip factor is made small in order to make the ring nearly isochronous and reduce the bunch length. What is found is that a quasi-isochronous ring makes it possible to obtain a bunch length in the millimeter range, about one order of magnitude shorter than present values. In this study the authors have extended the work of others on isochronous storage rings by quantitatively including higher-order terms in the longitudinal equations of motion. Scaling laws are then derived relating the linear term with the next-highest-order term. These scaling laws, which are derived from a two-dimensional Hamiltonian (one dimension of position and one of momentum), establish criteria for stability. These scaling laws are then checked with full six-dimensional tracking on one particular lattice. (13 References).
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title: Streak camera measurements of electron bunch length from a copper photocathode in an RF gun
format: conference proceeding
conference: PAC 1993
year: 1993
8 authors: G. Hairapetian | P. Davis | M. Everett | C. Clayton | C. Joshi | S. Hartman | S. Park | C. Pellegrini
abstract: Short laser pulses (sub 2 ps) of UV ( lambda =266 nm) light with 200 mu J/pulse are used to produce electrons from a copper cathode in an RF gun. The electron bunch length is measured by streaking the Cerenkov radiation ( lambda =530 nm) from a thin (250 mu m) fused silica etalon. Streaks for both 0 degrees and 70 degrees laser incidence angles with respect to the cathode normal are presented with a temporal resolution of 3.6 ps. The shortest electron bunch length measured was 9 ps. (3 References).
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title: Emittance measurements of the 4.5 MeV UCLA RF photoinjector
format: conference proceeding
conference: PAC 1993
year: 1993
10 authors: S. C. Hartman | N. Barov | S. Park | C. Pellegrini | J.B. 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).
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title: Design considerations for a 60 meter pure permanent magnet undulator for the SLAC Linac Coherent Light Source (LCLS)
format: conference proceeding
conference: PAC 1993
year: 1993
7 authors: R. Tatchyn | Boyce, R. | K. Halbach | Nuhn, H. D. | 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).
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title: Status of the variable momentum compaction storage ring experiment in SPEAR
format: conference proceeding
conference: PAC 1993
year: 1993
11 authors: Tran, P. | A. Amiry | C. Pellegrini | Corbett, J. | M. Cornacchia | Lee, M. | Nuhn, H. D. | H. Winick | Wu, D. | Hofmann, A. | D. Robin
abstract: Variable momentum compaction lattices have been proposed for electron-positron colliders and synchrotron radiation sources to control synchrotron tune and bunch length. To address questions of single particle stability limits, a study has been initiated to change the SPEAR lattice into a variable momentum compaction configuration for experimental investigation of the beam dynamics. In this paper, we describe a model-based method used to transform SPEAR from the injection lattice to the low momentum compaction configuration. Experimental observations of the process are reviewed. (12 References).
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title: A 2-4 nm Linac Coherent Light Source (LCLS) using the SLAC linac
format: conference proceeding
conference: PAC 1993
year: 1993
20 authors: H. Winick | K. Bane | R. Boyce | G. Loew | P. Morton | H. D. Nuhn | J. Paterson | P. Pianetta | T. Raubenheimer | J. Seeman | R. Tatchyn | V. Vylet | C. Pellegrini | J.B. Rosenzweig | G. Travish | D. Prosnitz | E. T. Scharlemann | K. Halbach | K. J. 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).
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title: Performance characteristics, optimization, and error tolerances of a 4 nm FEL based on the SLAC linac
format: conference proceeding
conference: PAC 1993
year: 1993
5 authors: K. J. Kim | M. Xie | E. T. Scharlemann | C. Pellegrini | G. Travish
abstract: A 4 nm free electron laser (FEL) operating in Self Amplified Spontaneous Emission (SASE), and using the SLAC linac as a driver has been extensively studied using the FRED3D and TDA3D codes. Using a 7 GeV beam with a normalized RMS emittance of 3 mm-mrad and a peak current of 2500 A, obtained by longitudinal bunch compression, the FEL can provide about 20 GWatt of peak power, in a subpicosecond pulse. The FEL saturation length is about 60 m. Strong focusing in both planes is provided throughout the undulator by a FODO quadrupole system. We have studied the system gain, its optimization and FEL tolerance to beam parameter changes, wiggler errors and misalignments. (14 References).
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title: A 2 to 4 nm high power FEL on the SLAC linac
format: conference proceeding
conference: FEL 1992 14th
year: 1993
13 authors: C. Pellegrini | J.B. Rosenzweig | Nuhn, H. D. | P. Pianetta | R. Tatchyn | H. Winick | Bane, K. | Morton, P. | T. Raubenheimer | J. Seeman | K. Halbach | K.J. Kim | Kirz, J.
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).
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title: Use of an inverse free electron laser in a linear collider B factory
format: conference proceeding
conference: AAC 1992 3rd
year: 1993
3 authors: C. Pellegrini | J. Sandweiss | N. Barov
abstract: The authors examine the possibility of using an IFEL as an accelerator in a linear collider B Factory. An IFEL is able to utilize a sizeable fraction of the energy of the laser pulse used to accelerate the beams. It is also able to meet the stringent requirements imposed on the energy spread and luminosity at the interaction point. Two separate examples are considered, differing in the way the laser pulse energy is coupled to the electron beam. The first maximizes the slippage between the beam bunch and the radiation, in order to decrease the peak laser power. In the second example the slippage is minimized. This results in uniform beam loading and may in principle be run at higher efficiency and lower average power. The authors also address the laser required to drive this accelerator. The power and frequency requirements suggest the use of a FEL drive laser. The design for this system includes the use of superconducting cavities to accelerate the drive beam, which is then propagated through an initially constant period undulator that is tapered after saturation.
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title: Photoelectron beams from the UCLA RF gun
format: conference proceeding
conference: AAC 1992 3rd
year: 1993
12 authors: S. Park | N. Barov | S. Hartman | C. Pellegrini | J.B. Rosenzweig | P. Tran | G. Travish | R. Zhang | P. Davis | G. Hairapetian | C. Joshi | N. Luhmann
abstract: A high brightness, low emittance photocathode rf gun is starting operation at UCLA as an injector to a 20 MeV linac. This linac will initially be used to drive FELs, plasma wakefield accelerators, and to test plasma lenses. The gun is a 1 1/2 cell pi-mode standing wave structure running at 2.856 GHz, and has a copper photocathode. In the initial commissioning of the gun, photoelectron beams of up to 2.5 nC at 4.5 MeV have been produced. We report on the current status of the system, experimental data taken with 50 ps UV laser pulses, and plans for the future.
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title: The UCLA IR FEL project
format: conference proceeding
conference: FEL 1992 14th
year: 1993
21 authors: G. Baranov | N. Barov | P. Davis | M. Fauver | B. Gitter | G. Hairapetian | S. Hartman | M. Hogan | S. Ivanchenkov | C. Joshi | A. Khlebnikov | P. Kwok | N. Luhmann | S. Park | C. Pellegrini | J.B. Rosenzweig | K. Schenk | Smolin, J. A. | P. Tran | G. Travish | A. A. Varfolomeev
abstract: A 10.6 mu m free electron laser (FEL) operating in the high gain regime is under construction at UCLA. FEL physics significant to future short wavelength operation is emphasized including optical guiding, superradiance, saturation and self-amplified spontaneous emission (SASE). A 5 MeV RF photocathode gun illuminated by a UV laser supplies a high brightness electron beam which is injected into a plane wave transformer (PWT) linac for acceleration to 20 MeV. Recent measurements of the gun emittance as well as quantum efficiency are presented. The undulator is of a modified hybrid design producing approximately 7.5 kG peak field on axis with 5 mm gap spacing and 1.5 cm pole period. Simulation results which include three-dimensional effects are furnished. The present status and future plans of the project are summarized. (16 References).
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title: The UCLA infrared free-electron laser
format: conference proceeding
conference: SPIE Conference on Intense Laser Beams
year: 1992
17 authors: J. W. Dodd | S. C. Hartman | S. Park | C. Pellegrini | J.B. Rosenzweig | J. A. Smolin | W. A. Barletta | D.B. Cline | R. K. Copper | J. Kolonko | J. G. Davis | G. Hairapetian | C. J. Joshi | N. C. Luhmann | S. N. Ivanchenkov | A. S. Khlebnikov | A. A. Varfolomeev
abstract: A compact 20 MeV linac with an RF laser-driven electron gun will drive a high-gain (10 cm gain length), 10.6 mu m wavelength FEL amplifier, operating in the SASE mode. FEL physics in the high-gain regime will be studied, including start-up from noise, optical guiding, sidebands, saturation, and superradiance, with emphasis on the effects important for future short wavelength operation of FELs. The hybrid undulator, designed and built at the Kurchatov Institute of Atomic Energy in the USSR has forty periods, each 1.5 cm long, the magnetic material is a hybrid combination of SmCo_5 blocks and Nd-Fe-B blocks, with vanadium-permendur yokes. The gap distance between pole-tips is fixed at 5 mm. On axis the peak value of the completed undulator's magnetic field was measured to be 7.3 kGauss (+/- 0.25%). Measurements during the conditioning phase of the RF gun for the electron beam's peak dark-current show 6 mA without the longitudinal magnetic focusing field in the gun and 34 mA with the focusing field active. The peak current from photoemission is calculated to be 200 A.
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title: Status of RF photoinjector and PWT linac at UCLA
format: conference proceeding
conference: Linear Accelerator Conference 1992
year: 1992
12 authors: S. Park | N. Barov | S. Hartman | C. Pellegrini | J.B. Rosenzweig | P. Tran | G. Travish | R. Zhang | P. Davis | G. Hairapetian | C. Joshi | N. Luhmann
abstract: The authors report the present status of RF photoinjector and plane wave transformer (PWT) linac for the production of 20 MeV/c electron beam. The photoinjector is a 1/sup 1///sub 2/ cell pi -mode standing wave structure operating at 2.856 GHz with photoelectrons generated on a copper cathode by 4 ps long laser pulse at 206 nm. Measurements of the beam of photoelectrons are underway at various experimental parameters. The PWT has been tested at low power to investigate its mode structure. An overview of the system, latest data, and future directions are presented. (5 References).
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title: Design and operation of a novel, compact 20 MeV linac at UCLA
format: conference proceeding
conference: Intense Microwave and Particle Beams II
year: 1992
9 authors: P.G. Davis | G. Hairapetian | C. Joshi | N. C. Luhmann | S. C. Hartman | S. Park | C. Pellegrini | J.B. Rosenzweig | J. A. 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).
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title: On Some Distinctiveness of the Kurchatov-UCLA Undulator Scheme Providing Strong Magnetic Fields for Short Periods
format: journal article
publisher:
year: September 1991
2 authors: C. Pellegrini | A. A. Varfolomeev
abstract: We present a qualitative analysis of the new scheme for the Kurchatov large field strengh short period undulator installed at UCLA and compare it with some hybrid schemes suggested by other laboratories. We show that beyond the apparent similarity important differences exist between these devices. As a result our design provides a higher saturation limit for the undulator magnetic fields.
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title: Operating Procedures for the UCLA Linear Accelerator Facility
format: tech note
year: February 14, 1991
2 authors: C. Pellegrini | C. Joshi
abstract: An RF laser-driven electron gun is being built at UCLA. This electron injector will be used to study the production of high-brightness electron beams, and to drive a high gain, free-electron laser amplifier. Other particle beam physics experiments include plasma wakefiled acceleration. All these experiments are performed under the umbrella of the Center for Advanced Accelerators located at the UCLA Linear Accelerator Laboratory.
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title: 40 Angstrom FEL designs for the PEP storage ring
format: conference proceeding
conference: FEL 1991 13th
year: 1992
6 authors: A.S. Fisher | J.C. Gallardo | Nuhn, H. D. | 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).
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title: Large-field-strength short-period undulator design
format: conference proceeding
conference: FEL 1991 13th
year: 1992
6 authors: A. A. Varfolomeev | S. N. Ivanchenkov | A. S. Khlebnikov | C. Pellegrini | Baranov, G. A. | Michailov, V. I.
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).
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title: Quasi-isochronous ring flavor factories
format: conference proceeding
conference: Conference on Rare and Exclusive B & K Decays and Novel Flavor Factories
year: 1992
2 authors: C. Pellegrini | D. Robin
abstract: The authors study the single particle and collective dynamics of a storage ring where the momentum compaction is made small to make the ring nearly isochronous and reduce the bunch length and increase the peak current. They find that a quasi-isochronous ring makes it possible to obtain a bunch length in the millimeter range, about one order of magnitude shorter than the present values, and to increase the beam longitudinal brillance by more than one order of magnitude. The shorter bunch length allows one to reduce the betatron function and the beam area at the interaction point of an electron-positron collider, leading to larger luminosity. They also design a ring whose momentum compaction can be varied over several orders of magnitude. (17 References).
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title: Remarks on the production of gravitational waves by EM radiation and particle beams
format: conference proceeding
conference: Workshop on Beam-Beam and Beam-Radiation Interactions: High Intensity and Nonlinear Effects
year: 1992
4 authors: Chen, P. | Diambrini-Palazzi, G. | K.J. Kim | C. Pellegrini
abstract: A report of the working group on the production of Gravitational Waves from electromagnetic radiation (EM) and particle beams. (9 References).
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title: The UCLA compact infrared free-electron laser
format: conference proceeding
conference: FEL 1991 13th
year: 1992
16 authors: J. W. Dodd | S. C. Hartman | S. Park | C. Pellegrini | J.B. Rosenzweig | D.B. Cline | G. Hairapetian | J. Kolonko | Smolin, J. A. | P.G. Davis | C. J. Joshi | N. Luhmann | S. N. Ivanchenkov | A. S. Khlebnikov | A. A. Varfolomeev | W. Barletta
abstract: The authors present the status of a compact infrared free-electron laser, driven by a 20 MeV, S-band linac with a photoinjector. The 60 cm long hybrid undulator has a 1.5 cm period and a field on axis of 7.3 kG. The FEL will operate at 10.6 mu m as a high-gain amplifier, to study the high-gain FEL regime including the effects of self amplified spontaneous emission, optical guiding and saturation. The linac is the prototype of the plane-wave transformer. TDA simulation of the FEL shows a gain length of 10 cm, and a saturation power of 50 MW. (18 References).
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title: Saturnus: the UCLA compact high-brightness linac
format: conference proceeding
conference: Conference on High-Brightness Beams for Advanced Accelerator Applications
year: 1992
1 author: C. Pellegrini
abstract: Saturnus is a compact S-band linac designed to produce a single bunch with an energy of 20 MeV, a peak current larger than 200 A on energy spread of 0.3%, an emittance smaller than 5 mm mrad (normalized rms), and a pulse duration of 4 ps or shorter. This bunch can be followed at a variable distance by a second weak 'witness' bunch, to be used to measure the field excited by the first bunch,. The linac electron injector is based on the Brookhaven photoinjector design. Solenoids are used to focus the beam from the gun through a mirror box and a plane wave transformer accelerating structure. The linac will be followed by two beam lines, one of them capable of longitudinal bunch compression, leading to experimental stations where beam-laser and beam plasma interactions will be studied. (4 References).
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title: Short wavelength FELs on large storage rings
format: conference proceeding
conference: National Conference on Synchrotron Radiation Instrumentation 7th
year: 1992
6 authors: H. D. Nuhn | R. Tatchyn | H. Winick | A.S. Fisher | J.C. Gallardo | C. Pellegrini
abstract: The use of a large-circumference, high-energy, electron-positron collider such as PEP, TRISTAN or PETRA to drive a free-electron laser (FEL), producing high levels of coherent power at short wavelengths around 40 AA is explored. The authors 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. As the electron beam passes down the undulator, its interaction with the increasingly intense spontaneous radiation causes a bunch density modulation at the optical wavelength, resulting in stimulated emission and exponential growth of coherent power in a single pass. The need for optical-cavity mirrors, which place a lower limit on the wavelength of a conventional FEL oscillator, is avoided. 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.
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title: Saturnus: the UCLA infrared free-electron laser project
format: conference proceeding
conference: PAC 1991
year: 1991
17 authors: J. W. Dodd | S. C. Hartman | S. Park | C. Pellegrini | J.B. Rosenzweig | Smolin, J. A. | G. Hairapetian | J. Kolonko | W. Barletta | D.B. Cline | J. G. Davis | C. J. Joshi | N. Luhmann | S. N. Ivanchenkov | A. S. Khlebnikov | Lachin, Y. Y. | A. A. Varfolomeev
abstract: A compact 20-MeV linac with an RF laser-driven electron gun will be used to drive a high-gain (10-cm gain length), 10.6- mu m wavelength FEL (free-electron laser) amplifier, operating in the SASE mode. Saturnus will mainly be used to study FEL physics in the high-gain regime, including start-up from noise, optical guiding, sidebands, saturation, and superradiance, with emphasis on the effects important for future short-wavelength operation of FELs. The primary magnetic flux is provided by C-shaped iron yokes, where between the poles thin blocks of neodymium-iron-boron magnets are placed to provide additional magnetic flux along the undulator axis. (9 References).
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title: Electron density enhancement in a quasi isochronous storage ring
format: conference proceeding
conference: PAC 1991
year: 1991
2 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).
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title: Quasi-isochronous storage ring
format: journal article
publisher: Nuclear Instruments & Methods A
year: 1991
2 authors: C. Pellegrini | D. Robin
abstract: The authors study the single particle and collective dynamics of a storage ring where the momentum compaction is made small to make it nearly isochronous, to reduce the bunch length and increase the peak current. They find that a quasi-isochronous ring makes it possible to obtain a bunch length in the millimeter range and to increase the beam longitudinal brilliance by more than one order of magnitude. (16 References).
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title: Isochronous storage-rings and high-luminosity electron-positron colliders
format: journal article
publisher: Annals of the NY Academy of Sciences
year: 1991
2 authors: C. Pellegrini | D. Robin
abstract:
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title: A high luminosity superconducting mini collider for phi meson production and particle beam physics
format: conference proceeding
conference: PAC 1991
year: 1991
14 authors: C. Pellegrini | D. Robin | D. B. Cline | J. Kolonko | S. Anderson | W. Barletta | Chargin, A. | M. Cornacchia | Dalbacka, G. | K. Halbach | Lueng, E. | Kimball, F. | Madura, D. | Patterson, L.
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).
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title: Preliminary conceptual design for a 510 MeV electron/positron injector for a UCLA phi factory
format: conference proceeding
conference: PAC 1991
year: 1991
4 authors: G. Dahlbacka | Hartline, R. | W. Barletta | C. Pellegrini
abstract: UCLA (University of California at Los Angeles) is proposing a compact superconducting high-luminosity (10(32-33)/ cm(-2)/ s(-1)) e+ e- collider for a phi factory. To achieve the required e+ e- currents, full energy injection from a linac with intermediate storage in a positron accumulator ring (PAR) is used. The elements of the linac are outlined with cost and future flexibility in mind. The preliminary conceptual design starts with a high current gun similar in design to those developed at SLAC and at ANL (for the APS). Four 4-section linac modules follow, each driven by a 60-MW klystron with a 1- mu s macropulse and an average current of 8.6 A. The first 4-section module is used to create positrons in a tungsten target at 186 MeV. The remaining three modules are used to accelerate the e+ e- beam to 558 MeV (no load limit) for injection into the PAR. (0 References).
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title: Photocathode driven linac at UCLA for FEL and plasma wakefield acceleration experiments
format: conference proceeding
conference: PAC 1991
year: 1991
17 authors: S. Hartman | F. Aghamir | W. Barletta | D. B. Cline | J. Dodd | T. Katsouleas | J. Kolonko | S. Park | C. Pellegrini | J.B. Rosenzweig | Smolin, J. A. | Terrien, C. | J. Davis | G. Hairapetian | C. Joshi | N. Luhmann | D. McDermott
abstract: The UCLA compact 20-MeV/c electron linear accelerators is designed to produce a single electron bunch with a peak current of 200 A, an RMS energy spread of 0.2% or less, and a short 1.2-ps RMS pulse duration. The linac is also designed to minimize emittance growth down the beamline so as to obtain emittances on the order of 8 pi mm-mrad in the experimental region. The linac will feed two beamlines, the first will run straight into the undulator for FEL experiments while the second will be used for diagnostics, longitudinal bunch compression and other electron beam experiments. A description is given of the considerations that went into the design of the accelerating structures and the transport to the experimental areas. (8 References).
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title: Saturnus: the UCLA compact infrared free-electron laser project
format: conference proceeding
conference: Intense Microwave and Particle Beams II
year: 1991
16 authors: J. W. Dodd | F. Aghamir | W. Barletta | D. B. Cline | S. C. Hartman | T. C. Katsouleas | J. Kolonko | S. Park | C. Pellegrini | P. G. Davis | C. J. Joshi | N. C. Luhmann | D. B. McDermott | S. N. Ivanchenkov | YuYu Lachin | A. A. Varfolomeev
abstract: Saturnus is an infrared FEL operating in the 10 mu m wavelength region, driven by a compact 20 MeV linac with a photoinjector, under construction at UCLA. The 1.5 cm period, 0.6 T peak field undulator is being built at the Kurchatov IAE. The FEL is designed to operate primarily in the self amplified spontaneous emission mode. The authors plan to study the start-up from noise, optical guiding, saturation, sidebands and superradiance, with emphasis on the effects important for future short wavelength operation of FEL's. The photoinjector follows closely the Brookhaven design. Electrons are injected into an accelerating section based on the plane-wave-transformer design developed by Swenson at SAIC. Simulation of the linac and FEL show a gain length of 10 cm, and a saturation power of 50 MW. (13 References).
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title: Coherent X-rays from PEP
format: conference proceeding
conference: PAC 1991
year: 1991
7 authors: S. Baird | Nuhn, H. D. | R. Tatchyn | H. Winick | A.S. Fisher | J.C. 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).
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title: Conceptual Design of a High Luminosity 510 MeV Collider
format: conference proceeding
conference: PAC 1991
year: 1991
3 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.
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title: The UCLA Phi-Factory Project
format: journal article
publisher:
year: 1991
1 author: C. Pellegrini
abstract:
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title: Remarks on short wavelength free electron lasers
format: conference proceeding
conference: Conference on Nonlinear and Relativistic Effects in Plasmas
year: 1992
1 author: C. Pellegrini
abstract: The author reviews the main physics issues and the scaling laws for short wavelength free electron lasers. The author discusses the two main operating modes, oscillator and self amplified spontaneous emission. The author also compares different electron beam drivers, like RF linacs and storage rings. The favourable scaling laws and the recent progress in FELs physics and technology show that the FEL is a good candidate for a tunable soft-X-ray laser. (38 References).
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title: Saturnus: the UCLA high-gain infrared FEL project
format: conference proceeding
conference: FEL 1990 12th
year: 1991
17 authors: F. Aghamir | W. Barletta | D.B. Cline | J. W. Dodd | S. C. Hartman | T.C. Katsouleas | J. Kolonko | S. Park | C. Pellegrini | Terrien, C. | J. G. Davis | C. J. Joshi | N. Luhmann | D. B. McDermott | S. N. Ivanchenkov | Lachin, Y. Y. | A. A. Varfolomeev
abstract: The authors present the status of Saturnus: an infrared FEL operating in the 10 mu m wavelength region, driven by a compact 20 MeV linac with a photoinjector, under construction at UCLA. The 1.5 cm period, 0.5 T peak-field undulator is being built at the Kurchatov IAE. The FEL is being designed to operate primarily in the self-amplified spontaneous emission mode. They plan to study the startup from noise, optical guiding, saturation, sidebands and superradiance, with emphasis on the effects important for future short-wavelength operation of FELs. The photoinjector follows closely the Brookhaven design. Electrons are injected into an accelerating section based on the plane-wave transformer design developed by Swenson at SAIC. Simulation of the linac and FEL show a gain length of 10 cm, and saturation power of 50 MW. (10 References).
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title: Quasi-isochronous storage ring: a novel concept for high luminosity lepton colliders
format: conference proceeding
conference: Present and Future of Collider Physics: Conference in Honour of Giorgio Salvini's 70th Birthday
year: 1991
2 authors: C. Pellegrini | D. Robin
abstract: The authors study the single particle and collective dynamics of a storage ring where the momentum compaction is made small to make the ring nearly isochronous and reduce the bunch length and increase the peak current. They find that a quasi-isochronous ring makes it possible to obtain a bunch length in the millimeter range, about one order of magnitude shorter than the present values, and to increase the beam longitudinal brilliance by more than one order of magnitude. The shorter bunch length allows one to reduce the betatron function and the beam area at the interaction point of an electron-positron collider, leading to larger luminosity. (16 References).
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title: A full energy positron source for the UCLA phi factory
format: conference proceeding
conference: Workshop on Testing CPT and Studying CP Violation at a Phi Factory
year: 1991
2 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).
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title: Optical klystron configuration for a high gain X-ray free-electron laser
format: journal article
publisher: Optics Communications
year: 1990
2 authors: J.C. Gallardo | C. Pellegrini
abstract: The authors present theory and numerical simulations of the performance of an X-ray free-electron laser in the amplified spontaneous emission mode with an optical klystron undulator configuration. This device can produce picosecond pulses of high brightness with a significantly shorter undulator than a conventional FEL. (13 References).
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title: Isochronous storage rings and high luminosity electron-positron colliders
format: conference proceeding
conference: Conference on Beam Dynamics Issues of High-Luminosity Asymmetric Collider Rings
year: 1990
2 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).
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title: A high-luminosity BB factory linear collider using positron recirculation and recovery
format: journal article
publisher: Nuclear Instruments & Methods A
year: 1990
2 authors: D. B. 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).
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title: Short wavelength FELs based on self amplified spontaneous emission
format: conference proceeding
conference: Conference on Free-Electron Lasers and Applications
year: 1990
1 author: C. Pellegrini
abstract: The experiment will utilize a single electron bunch traversing the undulators. Combining the three undulator parts the author explores the optical klystron and the self amplified spontaneous emission regime, optical guiding and other effects like sidebands instabilities and superradiance. After initial operation they will start a program to improve the beam characteristics using the radiation from the undulator as a diagnostic tool. As the beam quality improves one can also increase the beam energy and reduce the radiation wavelength. (49 References).
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title: The UCLA IR-FEL
format: conference proceeding
conference: IEEE International Conference on Plasma Science 1990
year: 1990
11 authors: F. Aghamir | W. Barletta | D. B. Cline | J. Dodd | S. Hartman | C. Joshi | J. Kolonko | N. Luhmann | D. McDermott | C. Pellegrini | C. Terrien
abstract: A high-brightness RF gun operating at 2.856 GHz is being used as the injector for an IR-FEL (free-electron laser) experiment. The RF gun consists of a disk loaded, 1.5 cell cavity and a photocathode in the end wall of the cavity. A strong electric field within the half cell near the photocathode quickly accelerates the electrons, thus preventing emittance blow-up. The photocathode is to be driven by a Nd:YAG laser system producing a 10-ps pulse. The power for the RF gun will be supplied by a 25-MW klystron. The RF power is coupled to the cavity via an S-band waveguide attached to the sidewall of the gun. The TE_10 mode excited in the waveguide strongly couples to the pi-mode with the RF gun while the zero mode is suppressed. (0 References).
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title: Optical-Klystron configuration for a high-gain X-ray free electron laser
format: conference proceeding
conference: FEL 1989 11th
year: 1990
2 authors: J.C. Gallardo | C. Pellegrini
abstract: Presents the theory and numerical simulations of the performance of an X-ray free electron laser in the amplified spontaneous-emission mode with an optical-klystron undulator configuration. This device can produce picosecond pulses of high brightness with a significantly shorter undulator than a conventional FEL. (10 References).
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title: A microwiggler free-electron laser at the Brookhaven Accelerator Test Facility
format: conference proceeding
conference: FEL 1989 11th
year: 1990
8 authors: Batchelor, K. | Ben-Zvi, I. | R. Fernow | J. Gallardo | H. Kirk | C. Pellegrini | van Steenbergen, A. | Bhowmik, A.
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).
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title: A linear collider phi factory and beam dynamics test machine
format: conference proceeding
conference: Workshop on CP Violation in Particle Physics and Astrophysics
year: 1990
8 authors: W.A. Barletta | R. C. Berg | A. Boden | C. Buchanan | D.B. Cline | A. Fridman | C. H. 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.
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title: Free electron lasers: development and applications
format: conference proceeding
conference: HEACC 1989 14th
year: 1990
1 author: 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).
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title: The Brookhaven Accelerator Test Facility injection system
format: conference proceeding
conference: PAC 1989
year: 1989
5 authors: X.J. Wang | H. G. Kirk | C. Pellegrini | McDonald, K. T. | Russell, D. P.
abstract: The Brookhaven Accelerator Test Facility (ATF) consists of a 50-MeV/c electron linac and a high-brightness RF gun, both operating at 2856 MHz. An extremely short (a few picoseconds) electron pulse with a low transverse emittance is generated by the RF gun. In order to preserve both longitudinal and transverse emittances, great care must be taken in transporting the electron beam from the RF gun to the linac. The injection line is described, first- and second-order lattice studies of the injection line are presented, and nonlinear effects on the emittance are studied. It is shown that it is possible to preserve transverse emittance in a low-energy beam-transfer line by use of slits and contoured edges of the dipole magnets. Bunch lengthening is induced by the large beam divergence out of the RF gun, thus requiring strong focusing. (11 References).
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title: Operational status of the Brookhaven National Laboratory Accelerator Test Facility
format: conference proceeding
conference: PAC 1989
year: 1989
18 authors: Batchelor, K. | Ben-Zvi, I. | Biglio, I. | Chou, T. S. | R. Fernow | Fischer, J. | J. Gallardo | H. G. Kirk | Kurnit, N. | McDonald, K. T. | Palmer, R. B. | Parsa, Z. | C. Pellegrini | Sheehan, J. | Srinivasan-Rao, T. | Ulc, S. | M. Woodle | van Steenbergen, A.
abstract: The design and operation of a 50-MeV electron linear accelerator utilizing a low emittance ( gamma epsilon =5 to 10 mm-mrad) radio-frequency gun operating at an output energy of 5 MeV and a charge of 1 nC are described. Design calculations, early radio-frequency measurements, and operational experience with the electron gun utilizing a dummy cathode in place of the proposed photocathode emitter are given. The dynamics of the electron beam coming off the photocathode has been modeled with the programs PARMELA and MASK. General agreement as to the expected characteristics of the electron beam at the RF-gun exit has been obtained using the two programs. It was also verified that, with proper matching of the transverse beam, no increase of the transverse normalized emittance occurs at the linac due to the fundamental RF mode. (5 References).
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title: Report on the Lake Arrowhead workshop on advanced acceleration concepts
format: conference proceeding
conference: PAC 1989
year: 1989
1 author: C. Pellegrini
abstract: The author reviews the present status of the field of new acceleration concepts, as presented at the Lake Arrowhead workshop, held at the beginning of 1989. It is pointed out that the field of advanced accelerator concepts has seen a remarkable progress during the last few years. Plasma and wakefield acceleration has been demonstrated. One can foresee similar progress in the area of laser acceleration when the Brookhaven ATF starts operation. Ideas for using plasmas to focus particle beams and to produce beam neutralization at the interaction point of a collider have also been developed. It is further noted that the development of high-brightness beams and high-gradient linacs can also have, in the near future, a strong impact on other fields, such as FELs (free-electron lasers) and synchrotron radiation sources. (43 References).
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title: The Brookhaven Accelerator Test Facility
format: conference proceeding
conference: Linear Accelerator Conference 1988
year: 1989
15 authors: K. Batchelor | T. S. Chou | R. C. Fernow | J. Fischer | J. Gallardo | H. G. Kirk | R. Koul | R. B. Palmer | C. Pellegrini | J. Sheehan | T. Srinivasan-Rao | S. Ulc | M. Woodle | N. Kurnit | K. T. McDonald
abstract: The Brookhaven Accelerator Test Facility (ATF) will consist of a 50-100 MeV/c electron linac and a 100 GW CO/sub 2/ laser system. A high brightness RF-gun operating at 2856 MHz is to be used as the injector into the linac. The RF-gun contains a Nd:Yag-laser-driven photocathode capable of producing a stream of six ps electron pulses separated by 12.5 ns. The maximum charge in a micropulse will be one nano-Coulomb. The CO/sub 2/ laser pulse length will be a few picoseconds and will be synchronized with the electron pulse. The design electron beam parameters are given and possible initial experiments are discussed. (9 References).
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title: A high brightness electron accelerator and its particle beam physics. Experimental program
format: conference proceeding
conference: INFN International School on Electromagnetic Radiation and Particle Beams Acceleration
year: 1989
1 author: 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).
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title: Theory of a free-electron laser with a Gaussian optical undulator
format: journal article
publisher: IEEE Journal of Quantum Electronics
year: 1988
4 authors: J.C. Gallardo | R. C. Fernow | Palmer, R. B. | C. Pellegrini
abstract: A theoretical study of the possibility of a free-electron laser in the XUV and soft X-ray region of the spectrum, using a counterpropagaing CO/sub 2/ laser beam as an undulator, is presented. A one-dimensional model is used to evaluate the single-pass power gain of such a device. The detrimental effects due to the energy speed, emittance of the electron beam, and the diffraction of the electromagnetic undulator are explicitly incorporated in the formalism. An oscillator experiment is also considered. The solutions of the optical pulse evolution equation in the weak field, low gain, and long-electron-pulse regimes are all derived. (27 References).
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title: Three dimensional simulation of high harmonic transverse optical klystron
format: conference proceeding
conference: FEL 1987 9th
year: 1988
4 authors: S.K. Dutt | Friedman, A. | A. Gover | C. Pellegrini
abstract: We present the results of a three dimensional simulation code, which calculates the parameters of coherent super-radiant harmonic frequency emission by electrons which are being bunched by an external laser beam while propagating in a planar undulator. This code was written in order to simulate the TOK experiment, which is presently underway at BNL. Instead of a full numerical simulation of Maxwell's equations and the electron force equations, a semi-analytical approach is adopted. Electron trajectories are computed analytically, and the radiation fields are expanded in terms of free space eigenmodes. Phase space and energy profiles of the electron beam are incorporated by a variable space sampling according to a given distribution function, rather than via Monte Carlo simulation. Computation time of about 0.1 s/electron was achieved with the present version of the code on the IBM 3090. We present the expected radiometric parameters as a function of the electron beam parameters (emittance and energy spread), and the modulating laser beam parameters (Rayleigh length, waist position and power). Statistical averaging is carried out by weighted averaging of the initial electron moments and energy phase space distribution. This approach results in the best prediction of the expected experimental measurement of the optical parameters which can be achieved with a finite number of sampling electrons (much smaller than in the experiment), without introducing artificial noise as in the Monte Carlo approach.
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title: Progress toward a soft X-ray FEL
format: conference proceeding
conference: FEL 1987 9th
year: 1988
1 author: C. Pellegrini
abstract: Reviews the FEL physics and obtains scaling laws for the extension of its operation to the soft X-ray region. The author also discusses the properties of an electron beam needed to drive such an FEL, and the present state of the art for the beam production. (17 References).
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title: The Trieste synchrotron radiation project
format: conference proceeding
conference: National Conference on Synchrotron Radiation Instrumentation 5th
year: 1988
7 authors: M. Cornacchia | M. Campagna | L. Fonda | G. Magaritondo | C. Pellegrini | R. Rosei | C. Rubbia
abstract: The present the project for a superhigh brilliance soft X-ray source at Trieste. At present the project is fully funded and the conceptual design is being developed. The facility, scheduled to become operational in 1992, will deliver unprecedented levels of brilliance, and will be used for a variety of experiments in physics, chemistry, materials science, engineering, biology, technology, and medical research, involving scientists from Italy, from a number of European countries, and from the USA. (2 References).
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title: Hamiltonian model of a free electron laser
format: journal article
publisher: Optics Communications
year: 1987
3 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).
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title: Introduction to the physics of the free electron laser
format: conference proceeding
conference: Joint US-CERN School of Particle Accelerators: Frontiers of Particle Beams
year: 1988
2 authors: J.B. 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.
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title: Feasibility study of a storage ring for a high-power XUV free-electron laser
format: journal article
publisher: Particle Accelerators
year: 1986
12 authors: J. Bisognano | S. Chattopadhyay | M. Cornacchia | A. Garren | K. Halbach | A. Jackson | K. J. 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).
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title: High-gain free electron lasers as generators of short wavelength coherent radiation
format: conference proceeding
conference: Conference on Short Wavelength Coherent Radiation: Generation and Applications
year: 1986
2 authors: K.J. 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).
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title: Electron-Positron Colliders in the TEV Region
format: conference proceeding
conference: International Symposium on Lepton and Photon Interactions at High Energies 1985
year: 1986
3 authors: G. Bonvicini | P. Gutierrez | C. Pellegrini
abstract: The authors review the main properties of e/sup +/e/sup -/ colliders, divided into 2 categories: storage rings and linear colliders; the basic physics, beam characteristics, limitations on beam current and density and their influence on the luminosity. (14 References).
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title: Design concepts of a storage ring for a high power XUV free electron laser
format: conference proceeding
conference: FEL 1985 7th
year: 1986
12 authors: M. Cornacchia | J. Bisognano | S. Chattopadhyay | A. Garren | K. Halbach | A. Jackson | K. J. Kim | H. Lancaster | J. Peterson | M. S. 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).
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title: Optimization of the parameters of a storage ring for a high power XUV free electron laser
format: conference proceeding
conference: International Conference on Insertion Devices for Synchrotron Sources
year: 1986
12 authors: A. Jackson | J. Bisognano | S. Chattopadhyay | M. Cornacchia | A. Garren | K. Halbach | K.J. Kim | H. Lancaster | J. Peterson | M. S. Zisman | C. Pellegrini | G. Vignola
abstract: The authors describe the operation of an XUV high gain FEL operating within a bypass of an electron storage ring, and discuss the implications on storage ring optimization imposed be FEL requirements. It transpires that, in the parameter regime of interest, collective effects within the beam play an important role. For example, intrabeam scattering dilutes the transverse emittance of the beam and the microwave instability increases the momentum spread. Both phenomena reduce the effectiveness of the FEL. A computer code, ZAP, has been written which, for a given lattice design, takes all such effects into consideration and produces a figure of merit for FEL operation for that machine. They show the results of ZAP for several storage ring designs, all optimized for FEL operation, and present a design example of a facility capable of producing coherent radiation at 400 AA with tens of megawatts of peak power. (24 References).
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title: High-energy inverse free-electron-laser accelerator
format: journal article
publisher: Physical Review A
year: 1985
3 authors: E. D. 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).
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title: High-energy inverse free-electron laser accelerator
format: conference proceeding
conference: Summer School on High Energy Particle Accelerators
year: 1985
3 authors: E. D. 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).
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title: Storage ring design for a short wavelength FEL
format: conference proceeding
conference: PAC 1985
year: 1985
12 authors: K. J. Kim | J. Bisognano | S. Chattopadhyay | M. Cornacchia | A. Garren | K. Halbach | A. Jackson | H. Lancaster | J. Peterson | M. Zisman | C. Pellegrini | G. Vignola
abstract: A high gain free electron laser (FEL) operating in a special bypass of a storage ring can provide tens of megawatts of coherent power at wavelengths shorter than 1000 AA. The requirements on beam qualities 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 approximately 10/sup -3/. Designing an electron storage ring with the required characteristics involves a comprehensive analysis of the restrictions 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. (12 References).
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title: Generation of high-intensity coherent radiation in the soft-X-ray and vacuum-ultraviolet region
format: journal article
publisher: Journal of the Optical Society of America B-Optical Physics
year: 1985
2 authors: J.B. 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).
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title: Collective Instability of a Free-Electron Laser Including Space-Charge and Harmonics
format: journal article
publisher: Optics Communications
year: 1985
3 authors: J.B. 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.
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title: A study for a 6 GeV undulator based synchrotron radiation source
format: conference proceeding
conference: PAC 1985
year: 1985
9 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).
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title: The classical theory of the transverse optical klystron for a nonmonoenergetic beam
format: journal article
publisher: Journal of Applied Physics
year: 1985
6 authors: I. Boscolo | M. Leo | R. A. Leo | G. Soliani | V. Stagno | C. Pellegrini
abstract: In this paper the classical theory of the transverse optical klystron is presented. The gain is obtained by solving analytically the Vlasov equation which governs the evolution of the electron beam along the undulator magnet. The initial energy distribution of the electron beam is assumed gaussian. Both the small signal and the saturation regime are investigated. (19 References).
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title: Free electron lasers for the XUV spectral region
format: conference proceeding
conference: FEL 1984 6th
year: 1985
2 authors: J.B. 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).
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title: A new method for pumping an optical klystron
format: conference proceeding
conference: International Workshop on Coherent and Collective Properties in the Interaction of Relativistic Electrons and Electromagnetic Radiation
year: 1985
8 authors: G. Vignola | R. R. Freeman | B.M. 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).
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title: Collective instabilities and high-gain regime in a free electron laser
format: journal article
publisher: Optics Communications
year: 1984
3 authors: R. Bonifacio | C. Pellegrini | L. M. 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).
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title: One-dimensional numerical simulation of a free electron laser-storage ring system
format: journal article
publisher: Journal of Applied Physics
year: 1984
2 authors: A. Luccio | C. Pellegrini
abstract: A numerical simulation of a free electron laser oscillator-storage ring system is presented. The model describes the evolution of the system toward a steady state and gives information on the change of the laser power and of the electron and photon pulse shape during the transient. The steady-state laser power output and electron beam properties are compared with the existing theoretical model. (17 References).
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title: The transverse optical klystron experiment at NSLS: laser harmonics into the XUV
format: conference proceeding
conference: Topical Meeting on Free Electron Generation of Extreme Ultraviolet Coherent Radiation
year: 1984
7 authors: B.M. Kincaid | R. R. Freeman | C. Pellegrini | A. Luccio | S. Krinsky | A. van Steenbergen | F. DeMartini
abstract: Describes the theory of the production of coherent XUV and soft X-rays using a transverse optical klystron (TOK). A TOK uses a high powered laser in conjunction with an undulator magnet to produce laser-like output of XUV radiation from the relativistic stored electron beam in the NSLS VUV electron storage ring. (13 References).
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title: Collective instabilities and high-gain regime free electron laser
format: conference proceeding
conference: Topical Meeting on Free Electron Generation of Extreme Ultraviolet Coherent Radiation
year: 1984
3 authors: R. Bonifacio | C. Pellegrini | L. M. 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).
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title: Conceptual design of a 300 GeV accelerator based on the Inverse Free Electron Laser mechanism
format: conference proceeding
conference: HEACC 1983 12th
year: 1983
3 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).
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title: Wiggler, undulator and free electron laser radiation sources development at the National Synchrotron Light Source
format: conference proceeding
conference: International Conference on X-Ray and VUV Synchrotron Radiation Instrumentation
year: 1983
5 authors: H. Hsieh | S. Krinsky | A. Luccio | C. Pellegrini | A. van Steenbergen
abstract: An overview is presented of the special radiation sources development at the NSLS for incorporation in a 2.5 GeV X-ray storage ring and a 700 MeV VUV storage ring. This includes a superconducting high field multipole wiggler, lambda /sub c/=0.5 AA; a permanent magnet wiggler, lambda /sub c/=2.0 AA; a maximum photon energy undulator (5-7 keV); an undulator for a soft X-ray line or 'continuum' spectrum and a free electron laser source tunable in the 2500-4500 AA region. Source characteristics and status of development are given. In addition, the incorporation of a backscattered Compton photon source is being studied and relevant parameters are presented. (22 References).
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title: The Brookhaven free electron laser experiment
format: conference proceeding
conference: Bendor Free Electron Laser Conference
year: 1983
5 authors: S. Krinsky | A. Luccio | C. Pellegrini | A. van Steenbergen | L. H. Yu
abstract: Reports on the status of the free electron laser experiment at Brookhaven with a description of the permanent undulator already built and ready to be installed on the VUV storage ring. (0 References).
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title: The inverse free-electron laser accelerator
format: conference proceeding
conference: Summer School on High Energy Particle Accelerators
year: 1983
2 authors: C. Pellegrini | I. E. Campisi
abstract: The authors discuss far field accelerators and in particular the 'inverse free-electron laser' which operates on the same principles as the free-electron laser. (14 References).
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title: A study on the conditions required for the transverse stability of a coasting beam in proton storage rings
format: journal article
publisher: Particle Accelerators
year: 1982
2 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).
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title: Report of the working group on far field accelerators
format: conference proceeding
conference: Workshop on the Laser Acceleration of Particles
year: 1982
1 author: C. Pellegrini
abstract: This report describes the work of the group on far field accelerators. The work concentrated on two accelerator schemes, the inverse free electron laser and the two wave device. The possibilities and limitations of these two accelerators are discussed, as well as some of the requirements on the laser necessary to reach very high energies. A conceptual design of a single pass inverse free electron laser is presented. (10 References).
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title: Single beam coherent instabilities in circular accelerators and storage rings
format: conference proceeding
conference: Summer School on High Energy Particle Accelerators
year: 1981
1 author: C. Pellegrini
abstract: The author discusses the meaning of coherent instabilities and illustrates the techniques that can be used to study this problem. He considers a particle and introduces the equations of motion for the case of longitudinal and transverse coherent oscillations. An expression for the longitudinal and transverse coherent is derived forces. There forces are then used in the Vlasov equations to obtain a dispersion relation and define the limiting conditions for stability. The longitudinal and transverse stabilities are discussed. (25 References).
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title: Longitudinal instabilities in circular accelerator and storage rings
format: conference proceeding
conference: PAC 1981
year: 1981
1 author: 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).
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title: Free electron laser experiment at the NSLS 700 MeV electron storage ring
format: conference proceeding
conference: PAC 1981
year: 1981
11 authors: J. P. Blewett | L. Blumberg | A. J. Campillo | R. P. DiNardo | H. C. Hsieh | S. Krinsky | A. Luccio | C. Pellegrini | J. Schuchman | P. Z. 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).
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title: On the condition for a single bunch high frequency fast blow-up
format: conference proceeding
conference: HEACC 1980 11th
year: 1980
2 authors: J.M. Wang | C. Pellegrini
abstract: The authors study the longitudinal stability of a single particle bunch in a storage ring using Vlasov equation. They show that the Vlasov equation has solutions corresponding to a fast, microwave instability if a condition on the beam current, qualitatively similar to the stability condition for a coasting beam, is satisfied. This condition can be used to define a threshold current, and to discuss its dependence on the longitudinal coupling impedance. (14 References).
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title: The free-electron laser and its possible developments
format: journal article
publisher: Synchrotron radiation research
year: 1980
1 author: C. Pellegrini
abstract: The operation of a free-electron laser has been discussed, emphasising its capabilities and limitations. The treatment was mainly concerned with operating the laser in an electron storage ring, including stimulated emission by relativistic electrons and in wiggler magnets. Some recent experiments at Stanford were reviewed (see e.g. Elias et al., 1976 and Deacon et al., 1977). (42 References).
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title: Phenomenological analysis of current limits in storage rings
format: conference proceeding
conference: Japanese/USA Seminar on Synchrotron Radiation Facilities
year: 1980
2 authors: C. Pellegrini | M. Sands
abstract: The authors report the limitations on the current which can be stored in a storage ring. A simple model is used for the impedance of the beam environment. They assume that feedback systems are used to their full capacity to provide beam stability and that in the frequency range where feedback can no longer be used Landau damping will determine how much current can be stored in the ring. Estimates are made for the proton storage rings and for the electron storage rings of interest as synchrotron radiation sources and for colliding beam systems for high energy physics. (13 References).
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title: UV free electron lasers for synchrotron radiation sources
format: conference proceeding
conference: Japanese/USA Seminar on Synchrotron Radiation Facilities
year: 1980
1 author: C. Pellegrini
abstract: The author discusses the possibility of operating a free electron laser in an electron storage ring similar to those being designed or built as synchrotron radiation sources. The laser output power is proportional to the total power radiated as synchrotron radiation in the ring. The electron beam properties make the storage ring particularly suitable for operating a laser in the UV region. Small signal gain per pass larger than one at wavelengths near 600 AA can be obtained in a 500 MeV storage ring. (16 References).
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title: Synchrotron radiation problems in storage ring version of FEL
format: conference proceeding
conference: ONR Workshop on Free-Electron Generators of Coherent Radiation 2nd
year: 1980
1 author: C. Pellegrini
abstract: The main properties of synchrotron radiation are reviewed. A semi-qualitative description is given of how synchrotron radiation determines the beam emittance in an electron storage ring and the importance of this for free electron laser operation. (9 References).
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title: The free electron laser and its possible developments
format: conference proceeding
conference: PAC 1979
year: 1979
1 author: C. Pellegrini
abstract: Reviews the basic characteristics, operating principles, applications and possible developments of a free electron laser in a storage ring. (18 References).
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title: Enhanced resistive wall instability for off-centred beams
format: conference proceeding
conference: PAC 1979
year: 1979
4 authors: E.D. Courant | M. Month | C. Pellegrini | J.M. 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).
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title: Beam-cavity interaction in electron storage rings
format: journal article
publisher: Nuclear Instruments & Methods
year: 1975
4 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).
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title: Colliding-beam accelerators
format: journal article
publisher: Annual review of nuclear science. Vol. 22.
year: 1972
1 author: 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).
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title: Diffraction radiation defocussing of an electron ring
format: journal article
publisher: Nuclear Instruments & Methods
year: 1971
3 authors: E. Keil | C. Pellegrini | A. M. 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.
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title: Two beam behaviour of the 1.5 GeV electron positron storage ring ADONE
format: conference proceeding
conference: HEACC 1971 8th
year: 1971
13 authors: F. Amman | M. Bassetti | A. Cattoni | V. Chimenti | D. Fabiani | M. Matera | C. Pellegrini | M. Placidi | M. Preger | A. Renieri | S. Tazzari | F. Tazzioli | G. Vignola
abstract:
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title: A study on the choice of parameters for a high energy electron ring accelerator
format: journal article
publisher: Particle Accelerators
year: 1971
2 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).
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title: The equilibrium length of high-current bunches in electron storage rings
format: journal article
publisher: Nuovo Cimento A
year: 1971
2 authors: C. Pellegrini | A. M. Sessler
abstract: The consequence of electrical interaction with various resonant structures is expressed in terms of quadratures over the impedance of the structures, and impedance functions for a variety of elements are evaluated. It is shown that elements having resonances at high frequency can, above transition, cause bunches to increase in length with increasing current. The parametric dependence of the bunch lengthening is found to be in good agreement with observations, and numerical estimates, which are in substantial agreement with experiment are presented. (16 References).
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title: A high energy proton-electron-positron colliding beam system
format: conference proceeding
conference: HEACC 1971 8th
year: 1971
6 authors: C. Pellegrini | J. Rees | B. Richter | M. Schwartz | D. Mohl | A. M. 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.
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title: Crossing of an incoherent integral resonance in the electron ring accelerator
format: journal article
publisher: Nuclear Instruments & Methods
year: 1970
2 authors: C. Pellegrini | A. M. 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)).
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title: Physics with and physics of colliding electron beams
format: journal article
publisher: Comments on Nuclear & Particle Physics
year: 1970
2 authors: C. Pellegrini | A. M. Sessler
abstract: The first section of this article deals with the physics that can be done with colliding beams. Experiments which have been already performed and those planned for the future are reviewed. The second section discusses the physics of colliding electron ring devices.
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title: Beam amplitude behavior upon crossing a linear coupling resonance with damping in one dimension
format: journal article
publisher: IEEE Transactions on Nuclear Science
year: 1969
4 authors: M. Lee | E. D. Courant | C. Pellegrini | A. M. 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.
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title: On a new instability in electron-positron storage rings (the head- tail effect)
format: journal article
publisher: Nuovo Cimento A
year: 1969
1 author: C. Pellegrini
abstract: It is shown that a bunched electron or positron beam of a storage ring can become unstable because of an effect not previously considered; the instability is due to the regenerative effect introduced by synchrotron oscillations, which enhances the action on the beam of rapidly decaying electromagnetic signals excited by the beam itself on its surrounding media. The results obtained show that the effect can produce instabilities for small beam currents (in the milliampere range), and that it can be influenced and reduced by properly choosing some parameters of the storage ring.
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