First Name: R.
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Last Name: Bonifacio
Full Name: R. Bonifacio
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14 papers
| title: | Research and development toward a 4.5-1.5 angstrom linac coherent light source (LCLS) at SLAC |
| format: | conference procceeding |
| conference: | 17th International Free Electron Laser Conference |
| year: | 1996 |
| 32 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| 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: | Spectrum, temporal structure, and fluctuations in a high-gain free-electron laser starting from noise |
| format: | unknown |
| year: | 1994 |
| 5 authors: | | | | | |
| 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: | Short wavelength FELs using the SLAC linac |
| format: | journal article |
| year: | 1994 |
| 30 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| 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 procceeding |
| conference: | 4th International Colloquium on X-Ray Lasers |
| year: | 1994 |
| 26 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | |
| 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: | Slippage, noise and superradiant effects in the UCLA FEL experiment |
| format: | conference procceeding |
| conference: | 15th International Free Electron Laser Conference |
| year: | 1994 |
| 5 authors: | | | | | |
| 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: | A Study of Linewidth, Noise and Fluctuations in a FEL Operating in SASE |
| format: | conference procceeding |
| conference: | 15th International Free Electron Laser Conference |
| year: | 1994 |
| 5 authors: | | | | | |
| 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: | A millimeter wave FEL driven by a photocathode RF linac |
| format: | conference procceeding |
| conference: | 15th International Free Electron Laser Conference |
| year: | 1994 |
| 11 authors: | | | | | | | | | | | |
| 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: | The SLAC soft X-ray high power FEL |
| format: | conference procceeding |
| conference: | 15th International Free Electron Laser Conference |
| year: | 1994 |
| 23 authors: | | | | | | | | | | | | | | | | | | | | | | | |
| 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: | Hamiltonian model of a free electron laser |
| format: | unknown |
| year: | 1987 |
| 3 authors: | | | |
| 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: | Collective Instability of a Free-Electron Laser Including Space-Charge and Harmonics |
| format: | unknown |
| year: | 1985 |
| 3 authors: | | | |
| 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: | Collective instabilities and high-gain regime in a free electron laser |
| format: | unknown |
| year: | 1984 |
| 3 authors: | | | |
| 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: | Collective instabilities and high-gain regime free electron laser |
| format: | conference procceeding |
| conference: | Topical Meeting on Free Electron Generation of Extreme Ultraviolet Coherent Radiation |
| year: | 1984 |
| 3 authors: | | | |
| 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: | Status of the SPARC-X Project |
| format: | journal article |
| year: | 2007 |
| 97 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| 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. |
| keywords: | pbpl |
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| title: | Single spike operation in SPARC SASE-FEL |
| format: | conference procceeding |
| conference: | EPAC 2008 |
| year: | |
| 16 authors: | | | | | | | | | | | | | | | | |
| abstract: | The single spike operation regime has been analyzed in the case of the SPARC injector and freeelectron-laser. Four different beams at 50 pC are studied, with different production condition and performance. |
| keywords: | pbpl_pub |
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