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M. Babzien

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33 papers
title: Observation of redshifting and harmonic radiation in inverse Compton scattering
format: journal article
publisher:
year: 2015
21 authors: Y. Sakai | I. Pogorelsky | O. Williams | F.H. O'Shea | S. Barber | I. Gadjev | J. Duris | P. Musumeci | M. Fedurin | A. Korostyshevsky | B. Malone | C. Swinson | G. Stenby | K. Kusche | M. Babzien | M. Montemagno | P. Jacob | Z. Zhong | M. Polyanskiy | V. Yakimenko | J.B. Rosenzweig
abstract: Inverse Compton scattering of laser photons by ultrarelativistic electron beam provides polarized x- to γ-ray pulses due to the Doppler blueshifting. Nonlinear electrodynamics in the relativistically intense linearly polarized laser field changes the radiation kinetics established during the Compton interaction. These are due to the induced figure-8 motion, which introduces an overall redshift in the radiation spectrum, with the concomitant emission of higher order harmonics. To experimentally analyze the strong field physics associated with the nonlinear electron-laser interaction, clear modifications to the angular and wavelength distributions of x rays are observed. The relativistic photon wave field is provided by the ps CO2 laser of peak normalized vector potential of 0.5
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title: Resonant excitation of coherent Cerenkov radiation in dielectric lined waveguides
format: journal article
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year: 2011
12 authors: G. Andonian | O. Williams | X. Wei | P. Niknejadi | E. Hemsing | J. B. Rosenzweig | P. Muggli | M. Babzien | M. Fedurin | K. Kusche | R. Malone | V. Yakimenko
abstract: We report the observation of coherent Cerenkov radiation in the terahertz regime emitted by a relativistic electron pulse train passing through a dielectric lined cylindrical waveguide. We describe the beam manipulations and measurements involved in repetitive pulse train creation including comb collimation and nonlinear optics corrections. With this technique, modes beyond the fundamental are selectively excited by use of the appropriate frequency train. The spectral characterization of the structure shows preferential excitation of the fundamental and of a higher longitudinal mode.
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title: Dielectric Wakefield Acceleration of a Relativistic Electron Beam in a Slab-Symmetric Dielectric Lined Waveguide
format: journal article
publisher: Physical Review Letters
year: 15 June 2012
13 authors: G. Andonian | D. Stratakis | M. Babzien | S. Barber | M. Fedurin | E. Hemsing | K. Kusche | P. Muggli | B. O'Shea | X. Wei | O. Williams | V. Yakimenko | and J.B. Rosenzweig
abstract: We report first evidence of wakefield acceleration of a relativistic electron beam in a dielectric-lined slab-symmetric structure. The high energy tail of a ?60??MeV electron beam was accelerated by ?150??keV in a 2 cm-long, slab-symmetric SiO2 waveguide, with the acceleration or deceleration clearly visible due to the use of a beam with a bifurcated longitudinal distribution that serves to approximate a driver-witness beam pair. This split-bunch distribution is verified by longitudinal reconstruction analysis of the emitted coherent transition radiation. The dielectric waveguide structure is further characterized by spectral analysis of the emitted coherent Cherenkov radiation at THz frequencies, from a single electron bunch, and from a relativistic bunch train with spacing selectively tuned to the second longitudinal mode (TM02). Start-to-end simulation results reproduce aspects of the electron beam bifurcation dynamics, emitted THz radiation properties, and the observation of acceleration in the dielectric-lined, slab-symmetric waveguide.
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title: Chicane Radiation Measurements with a Compressed Electron Beam at the BNL ATF
format: conference proceeding
conference: PAC 2007
year: 2007
12 authors: G. Andonian | R. Agustsson | A.M. Cook | M. Dunning | E. Hemsing | A. Murokh | Sven Reiche | J.B. Rosenzweig | M. Babzien | K. Kusche | R. Malone | V. Yakimenko
abstract: The radiation emitted from a chicane compressor has been studied at the Brookhaven National Laboratory (BNL) Accelerator Test Facility (ATF). Coherent edge radiation (CER) is emitted from a compressed electron beam as it traverses sharp edge regions of a magnet. The compression is accompanied by strong self-fields, which are manifested as distortions in the momentum space called beam bifurcation. Recent measurements indicate that the bunch length is approximately 100 fs rms. The emitted THz chicane radiation displays strong signatures of CER. This paper reports on the experimental characterization and subsequent analysis of the chicane radiation measurements at the BNL ATF with a discussion of diagnostics development and implementation. The characterization includes spectral analysis, far-field intensity distribution, and polarization effects. Experimental data is benchmarked to a custom developed start-to-end simulation suite.
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title: Characterization of Orbital Angular Momentum Modes in FEL Radiation
format: conference proceeding
conference: PAC 2007
year: 2007
5 authors: E. Hemsing | G. Andonian | J.B. Rosenzweig | M. Babzien | V. Yakimenko
abstract: It is well known that Gaussian modes of paraxial light can possess orbital angular momentum (OAM) as a result of a exp( ?il?) azimuthal angular dependence[1]. Recent experiments on the VISA free-electron laser operating as self-amplified spontaneous amplifier (SASE) at ?=840 nm have produced transverse electromagnetic radiation inten- sity patterns that suggest the presence of one or more OAM modes. Though the intensity profiles from VISA are com- pelling, work remains to discern the phase structure since OAM modes are revealed by a characteristic helical phase dependence, with a pathological singularity on axis. Here we discuss current efforts to characterize the mode content of the VISA FEL through experiments, theoretical mod- els, and simulations. Possible methods to generate OAM modes in situ are discussed.
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title: Seeded VISA: A 1064 nm Laser-Seeded FEL Amplifier at the BNL ATF
format: conference proceeding
conference: PAC 2007
year: 2007
7 authors: M. Dunning | G. Andonian | E. Hemsing | S. Reiche | J.B. Rosenzweig | M. Babzien | V. Yakimenko
abstract: An experimental study of a seeded Free Electron Laser (FEL) using the VISA undulator and a Nd:YAG seed laser will be performed at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory. The study is motivated by the demand for a short Rayleigh length FEL amplifier at 1 micron to allow for high power transmission with min- imal damage of transport optics. Planned measurements include transverse and longitudinal coherence, angular dis- tribution, and wavelength spectrum of the FEL radiation. The effects of detuning the electron beam energy will be studied, with an emphasis on control of the radiation emis- sion angles and increase of the amplifier efficiency. Results of start-to-end simulations are also presented.
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title: Beam compression experiments using the UCLA/ATF compressor
format: conference proceeding
conference: AAC 2006 12th
year: 2006
13 authors: D. Schiller | E. Hemsing | J.B. Rosenzweig | M.P. Dunning | G. Andonian | A. Murokh | A.M. Cook | Sven Reiche | M. Babzien | K. Kusche | V. Yakimenko | L. Palumbo | C. Vicario
abstract: We review recent experimental results from the BNL ATF using the compressor built by UCLA. The measurements discussed include: first observation of short wavelength coherent edge radiation angular/wavelength spectrum and spectrum, sub-100 fsec pulse-length coherent transition autocorrelation measurements, and longitudinal and transverse phase space distortions. Extension of these measurements, as well as those which can be made possible by a new X-band traveling wave deflector being developed in an industrial collaboration, are examined.
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title: Magnetic Chicane Radiation Studies at the BNL ATF
format: conference proceeding
conference: FEL 2006 28th
year: 2006
11 authors: M.Dunning | G. Andonian | A.M. Cook | E. Hemsing | A.Murokh | Sven Reiche | J.B. Rosenzweig | D. Schiller | M. BABZIEN | K. Kusche | V. Yakimenko
abstract: Radiation emitted by relativistic electrons traversing the magnetic field gradients of a chicane bunch compressor has been studied in an attempt to characterize coherent edge radiation (CER). The studies performed at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL) include frequency spectrum, angular distribution, and polarization measurements. A reconstruction of the longitudinal charge profile from the measured spectrum shows that the bunch has been compressed to approximately 30 ?m FWHM, with a peak current exceeding 1.5 kA. Measurements of radiation from the short pulses are compared to predictions from QUINDI, a new simulation code developed at UCLA to model the radiation.
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title: Future FEL Studies at the VISA Experiment in the SASE and Seeded Modes
format: journal article
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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: Observation of Coherent Edge Radiation Emitted by a 100 Femtosecond Compressed Electron Beam
format: conference proceeding
conference: ICFA Workshop on Physics and Applications of High Brightness Electron Beams
year: 2006
14 authors: G. Andonian | M. Dunning | E. Hemsing | J.B. Rosenzweig | A. M. Cook | A. Murokh | S. Reiche | M. Babzien | I. Ben-Zvi | K. Kusche | V. Yakimenko | D. Alesini | L. Palumbo | C. Vicario
abstract: A chicane compressor developed by UCLA for the production of ultra-short, 60 MeV electron beams at the Brookhaven National Laboratory Accelerator Test Facility has been commissioned, and initial beam physics experiments have been performed. These measurements have established the compression of electron beams to the 100 femtosecond (1 kA peak current) regime, via coherent transition radiation (CTR) based measurements. Investigations of coherent edge radiation (CER) include signatures that differentiate it from coherent synchrotron radiation (CSR), such as polarization and far-field angular distribution. Additionally, the radiation wavelength spectrum is determined from autocorrelation measurements. Radiation properties are compared to detailed start-to-end simulations derived from PARMELA and QUINDI (a Lienard-Wiechert code developed at UCLA). Plans for future experiments which further explore the observed wavelength spectra are presented.
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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: 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: 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: 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 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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. C. 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: The operation of the BNL/ATF GUN-IV photocathode RF gun at the Advanced Photon Source
format: conference proceeding
conference: PAC 1999
year: 1999
18 authors: S. G. Biedron | G. A. Goeppner | J. W. Lewellen | S. V. Milton | A. Nassiri | G. Travish | X. J. Wang | N. D. Arnold | W. J. Berg | M. Babzien | C. L. Doose | R. J. Dortwegt | A. Grelick | J. N. Galayda | G. M. Markovich | S. J. Pasky | J. G. Power | B. X. Yang
abstract: At the Advanced Photon Source (APS) at Argonne National Laboratory (ANL), a free-electron laser (FEL) based on the self-amplified spontaneous emission (SASE) process is nearing completion. Recently, an RF photoinjector gun system was made available to the APS by Brookhaven National Laboratory/Accelerator Test Facility (BNL/ATF). It will be used to provide the high-brightness, low-emittance, and low-energy spread electron beam required by the SASE FEL theory. A Nd:Glass laser system, capable of producing a maximum of 500 mu J of UV in a 1-10 ps pulse at up to a 10-Hz repetition rate, serves as the photoinjector's drive laser. Here, the design, commissioning, and integration of this gun with the APS are discussed. (8 References).
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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: 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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