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ABSTRACT: In a recent paper it has been shown that single electron Thomson backscatter calculations can be performed including the effects of pulsed high intensity lasers. In this paper we present a more detailed treatment of the problem and present results for more general scattering geometries. In particular, we present new results for 90 degrees Thomson scattering. Such geometries have been increasingly studied as x-ray sources of short-pulse radiation. Also, we present a clearer physical basis for these different cases.
Physical Review E 12/2005; 72(5 Pt 2):056502. · 2.26 Impact Factor
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ABSTRACT: An Inverse Compton Scattering (ICS) experiment, which will investigate nonlinear properties of scattering utilizing a terawatt CO 2 laser system with various polarizations, is ongoing at the UCLA Neptune Laboratory. When the normalized amplitude of the incident laser's vector potential a 0 is larger than unity the scattering occurs in the nonlinear region; therefore, higher harmonics are also produced. ICS can be used, e.g., for a polarized positron source by striking a thin target (such as tungsten) with the polarized X-rays. As such, it is critical to demonstrate the production of polarized scattered photons and to investigate the ICS process as it enters the nonlinear regime. We present the description of the experimental set up and equipment utilized, including diagnostics for electron and photon beam detection. We present the current status of the experiment.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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J. Lim, A. Doyuran,
P. Frigola,
G. Travish,
J. Rosenzweig,
S. Anderson,
S. Betts,
J. Crane,
D. Gibson,
F. Hartemann,
A. Tremaine
[show abstract]
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ABSTRACT: We describe an experiment for production of high harmonic x-ray radiation from Thomson backscattering of an ultra-short high power density laser by a relativistic electron beam at the PLEIADES facility at LLNL. In this scenario, electrons execute a “figure-8” motion under the influence of the high-intensity laser field, where the con stant characterizing the field strength is expected to exceed unity: a L = eE L /m e cω L ≥ 1. With large a L this motion produces high harmonic x-ray radiation and significant broadening of the spectral peaks. This paper is intended to give a layout of the PLEIADES experiment, along with progress towards experimental goals.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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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. Varfolomeev,
S. Tolmachev,
A. Varfolomeev Jr,
T. Yarovoi
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ABSTRACT: We report on 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 a 50 cm long undulator strongly tapered both in period and field amplitude. A CO 2 10.6 µ m laser with power > 400 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 dominated. 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.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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P Musumeci,
S Ya Tochitsky,
S Boucher,
C E Clayton, A Doyuran,
R J England,
C Joshi,
C Pellegrini,
J E Ralph,
J B Rosenzweig,
C Sung,
S Tolmachev,
G Travish,
A A Varfolomeev,
T Yarovoi,
R B Yoder
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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 field amplitude. The Rayleigh range of the laser, approximately 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.
Physical Review Letters 05/2005; 94(15):154801. · 7.37 Impact Factor
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L H Yu,
L DiMauro, A Doyuran,
W S Graves,
E D Johnson,
R Heese,
S Krinsky,
H Loos,
J B Murphy,
G Rakowsky,
J Rose,
T Shaftan,
B Sheehy,
J Skaritka,
X J Wang,
Z Wu
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ABSTRACT: We report the first experimental results on a high-gain harmonic-generation (HGHG) free-electron laser (FEL) operating in the ultraviolet. An 800 nm seed from a Ti:sapphire laser has been used to produce saturated amplified radiation at the 266 nm third harmonic. The results confirm the predictions for HGHG FEL operation: stable central wavelength, narrow bandwidth, and small pulse-energy fluctuation.
Physical Review Letters 09/2003; 91(7):074801. · 7.37 Impact Factor
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ABSTRACT: A new RF control system was designed and implemented to support short pulse High Gain Harmonic Generation (HGHG) experiments, which require subpicosecond synchronization between the laser and the accelerating RF fields. This control system consists of a 81 MHz crystal oscillator to drive both the Ti::Sapphire laser and a 2856 MHz synthesizer, direct vector modulators that control the amplitude and phase of the klystron drive and vector de-modulators for amplitude and phase measurement. RF and electron beam based measurement results of the RF to laser jitter are presented as well as experimental results of synthesizing the RF directly from the 81.6 MHz pump laser pulse train.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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A. Doyuran,
L. DiMauro,
W. Graves,
R. Heese,
E.D. Johnson,
S. Krinsky,
H. Loos,
J.B. Murphy,
G. Rakowsky,
J. Rose,
T. Shaftan,
B. Sheehy,
Y. Shen,
J. Skaritka,
X.J. Wang,
Z. Wu,
L.H. Yu
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ABSTRACT: The Deep Ultra Violet Free Electron Laser (DUV-FEL) experiment has reached a milestone by saturating the Free Electron Laser using High Gain Harmonic Generation (HGHG) method in the Source Development Laboratory (SDL) at NSLS. It utilizes the 10 m long, 3.9 cm period NISUS wiggler. The goal of the project is to produce radiation at a wavelength less than 100 nm, utilizing the HGHG method. HGHG at 266 nm has been accomplished by seeding with the 800 nm Ti:Sapphire laser and observed saturation. The third harmonic at 88 nm accompanying the 266 nm is being used in an ion pair imaging experiment in chemistry. We discuss the measurement of energy, gain, spectrum, and pulse length of the FEL output. We also describe the diagnostics used for operating the FEL.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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H. Loos, A. Doyuran,
J.B. Murphy,
J. Rose,
T. Shaftan,
B. Sheehy,
Y. Shen,
J. Skaritka,
X.J. Wang,
Z. Wu,
L.H. Yu
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ABSTRACT: The linac at the NSLS Source Development Lab (SDL) provides a high brightness electron beam for the DUV-FEL project with subpicosecond bunch length and several hundred Amperes peak current by means of a photoinjector and a magnetic bunch compressor. Previous diagnostics of the longitudinal bunch dynamics relied on the rf zero-phasing method and measurements of CTR spectra. In order to have a fast and nonintercepting longitudinal diagnostic available, the electro-optic measurement technique has been implemented with its major component, a synchronized 100 fs Ti:sapphire laser coaligned with the electron beam, already in place as a seed for the FEL. The theoretical temporal resolution for a 100 μm thick ZnTe crystal is limited to about 200 fs and the signal contrast to more than 1%. We present preliminary results of multishot scanning measurements and the single-shot diagnostics of the bunch shape as well as its application as a rf-laser jitter monitor.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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B. Podobedov,
J.M. Ablett,
L. Berman,
R. Biscardi,
G.L. Carr,
B. Casey,
S. Dierker, A. Doyuran,
R. Heese,
S. Hulbert, [......],
R. Pindak,
S. Pjerov,
J. Rose,
T. Shaftan,
B. Sheehy,
P. Siddons,
N. Towne,
J.M. Wang,
X.J. Wang,
L.H. Yu
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ABSTRACT: To address the growing needs of the NSLS user community we are aggressively pursuing R&D towards a facility upgrade. The present goals are a 3 GeV ultra-low emittance storage ring, tailored to the 5-20 keV photon energy range, that will triple the present NSLS ID capacity, and provide three orders of magnitude increase in brightness over the present brightest NSLS beamlines. To achieve these goals we propose a 24 period TBA lattice, with extensive use of super-conducting small gap undulators. This paper reviews our preliminary design and the key accelerator physics issues.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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L Dimauro, A Doyuran,
W Graves,
R Heese,
E D Johnson,
S Krinsky,
H Loos,
J B Murphy,
G Rakowsky,
J Rose,
T Shaftan,
B Sheehy,
J Skaritka,
X J Wang,
L H Yu
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ABSTRACT: The Deep Ultra-Violet Free Electron Laser (DUVFEL) at the National Synchrotron Light Source consists of a 5 MeV photoinjector, a 200 MeV S-band linear accelerator, a four-magnet chicane compressor and a 10 m wiggler with a 3.9 cm period. The commissioning of the SDL accelerator was completed recently and it is routinely producing a high-quality electron beam with a peak current of B400 A and a normalised emittance of 3–4 mm mrad. The first SASE lasing of the DUV FEL has been demonstrated at both 266 and 400 nm. The gain length of the SASE experiments was measured to be 66 cm in both cases and up to 20 nJ per pulse was obtained. A laser seeded FEL at 266 nm is in the very early stages of commissioning and amplification of the laser seed has been observed. The goal of the seeded laser FEL is to saturate the FEL and thereby generate sufficient third harmonic at 89 nm for experimental applications. Here we report the observation and measurements of SASE at 400 and 266 nm and the first results of seeded FEL. r 2003 Elsevier Science B.V. All rights reserved.
Nuclear Instruments and Methods in Physics Research A. 01/2003; 507:15-18.
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ABSTRACT: The emittance of a high-brightness electron beam from a photoinjector is affected by the transverse and longitudinal distributions of the laser beam illuminating the cathode. A nonuniform laser beam generates a nonuniform electron-beam distribution that experiences emittance growth on a time scale of the plasma period. Experiments were performed at the Brookhaven Accelerator Test Facility to investigate the emittance growth due to transversely nonuniform laser beams. Laser masks were fabricated to generate various laser distributions. Significant emittance growth was observed as the laser distribution deviated strongly from a uniform distribution. For cylindrically symmetric, nonuniform distributions, experimental results agree with PARMELA simulations. The emittance dependence on the bunch charge is linear as a function of the bunch charge for both uniform and nonuniform beams. For a uniform beam, the emittance measurements agree well with the predictions from PARMELA simulations, but the analytical approach overestimates the results. For nonuniform beams, analytical estimates are about 70% of the measurements. For noncylindrically symmetric, nonuniform beams, we observed that the emittance is linearly proportional to the rms laser nonuniformity and the best emittance for a perfectly uniform beam is extrapolated to be 1:07 0:13 mm mrad at 0.5 nC.
Physical Review Special Topics - Accelerators and Beams 09/2002; · 1.52 Impact Factor
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A Doyuran,
M Babzien,
T Shaftan,
L H Yu,
L F DiMauro,
I Ben-Zvi,
S G Biedron,
W Graves,
E Johnson,
S Krinsky,
R Malone,
I Pogorelsky,
J Skaritka,
G Rakowsky,
X J Wang,
M Woodle,
V Yakimenko,
J Jagger,
V Sajaev,
I Vasserman
[show abstract]
[hide abstract]
ABSTRACT: We report on an experimental investigation characterizing the output of a high-gain harmonic-generation (HGHG) free-electron laser (FEL) at saturation. A seed CO2 laser at a wavelength of 10.6 microm was used to generate amplified FEL output at 5.3 microm. Measurement of the frequency spectrum, pulse duration, and correlation length of the 5.3 microm output verified that the light is longitudinally coherent. Investigation of the electron energy distribution and output harmonic energies provides evidence for saturated HGHG FEL operation.
Physical Review Letters 07/2001; 86(26 Pt 1):5902-5. · 7.37 Impact Factor
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W. Graves,
G. Carr,
L.R. DiMauro, A. Doyuran,
R. Heese,
E.D. Johnson,
S. Krinsky,
C. Neuman,
G. Rakowsky,
J. Rose,
J. Rothman,
J. Rudati,
T. Shaftan,
B. Sheehy,
J. Skaritka,
L.-H. Yu,
D.H. Dowell,
P. Emma
[show abstract]
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ABSTRACT: The DUVFEL electron linac is designed to produce sub-picosecond,
high brightness electron bunches to drive an ultraviolet FEL. The
accelerator consists of a 1.6 cell S-band photoinjector, variable pulse
length Ti:Sapp laser, 4 SLAC-type S-band accelerating sections, and
4-dipole chicane bunch compressor. In preparation for FEL operation, the
compressed electron beam has been fully characterized. Measurement of
the beam parameters and simulation of the beam are presented
Particle Accelerator Conference, 2001. PAC 2001. Proceedings of the 2001; 02/2001
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L.-H. Yu,
L.F. DiMauro, A. Doyuran,
W. Graves,
E. Johnson,
S. Krinsky,
S. Mikhailov,
G. Rakowsky,
J. Skaritka,
T. Shaftan,
B. Sheehy,
J.H. Wu
[show abstract]
[hide abstract]
ABSTRACT: We discuss the design and output radiation parameters for the Deep
Ultra-violet Free Electron Laser at BNL, which will generate coherent
output down to 100 nm using high gain harmonic generation. The result of
the FEL calculation and the status of the experiment are presented
Particle Accelerator Conference, 2001. PAC 2001. Proceedings of the 2001; 02/2001
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T. Shaftan,
M. Babzien,
I. Ben-Zvi,
S.G. Biedron,
L.F. DiMauro, A. Doyuran,
W. Graves,
J. Jagger,
E. Johnson,
S. Krinsky, [......],
B. Sheehy,
J. Skaritka,
L. Solomon,
G. Rakowsky,
I. Vasserman,
J.H. Wu,
X.J. Wang,
M. Woodle,
V. Yakimenko,
L.-H. Yu
[show abstract]
[hide abstract]
ABSTRACT: We report on observations of the output of a high-gain
harmonic-generation (HGHG) free-electron laser (FEL) at saturation. A
seed CO<sub>2</sub> laser at a wavelength of 10.6 μm was used to
generate amplified FEL output at 5.3 μm. Measurement of the frequency
spectrum, pulse duration and correlation length of the 5.3-μm output
verified the longitudinal coherence of the light. At the exit of the
device, measurements of the energy distribution of the electron beam
indicated that the HGHG process had reached saturation. By comparing the
intensities of the higher harmonics (2.65 μm and 1.77 μm) relative
to the 5.3-μm fundamental, additional evidence confirming saturated
operation was obtained. These results agree with theoretical predictions
at saturation. We also briefly describe the status of a new HGHG
experiment at the Source Development Laboratory (BNL), aimed at
achieving generation of 100-nm radiation
Particle Accelerator Conference, 2001. PAC 2001. Proceedings of the 2001; 02/2001
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W.S. Graves,
G.L. Carr,
L.F. DiMauro, A. Doyuran,
R. Heese,
E.D. Johnson,
C. Neuman,
G. Rakowsky,
J. Rose,
J. Rudati,
T. Shaftan,
B. Sheehy,
J. Skaritka,
L.-H. Yu,
D.H. Dowell
[show abstract]
[hide abstract]
ABSTRACT: The DUVFEL electron linac is designed to produce sub-picosecond,
high brightness electron bunches for driving a short wavelength FEL.
Four experiments have been commissioned to address the challenge of
accurately measuring bunch lengths on this timescale. In the frequency
domain, a short 12 period undulator is used to produce both off-axis
coherent emission and on-axis incoherent single-shot spectra. The total
coherent infrared power scales inversely with the bunch length and the
spectral cutoff is an indication of bunch length. The density of the
power spikes in the single-shot visible spectrum may also be used to
estimate the bunch length. In the time domain, the linac accelerating
sections and a bending magnet are used to implement the RF-zero phasing
method, and a subpicosecond streak camera is also installed. The beam
measurements with comparisons of these methods are reported
Particle Accelerator Conference, 2001. PAC 2001. Proceedings of the 2001; 02/2001
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A Doyuran,
M Babzien,
T Shaftan,
S G Biedron,
L H Yu,
I Ben-Zvi,
L F Dimauro,
W Graves,
E Johnson,
S Krinsky,
R Malone,
I Pogorelsky,
J Skaritka,
G Rakowsky,
X J Wang,
M Woodle,
V Yakimenko,
J Jagger,
V Sajaev,
I Vasserman
[show abstract]
[hide abstract]
ABSTRACT: We report on the experimental investigation of high-gain harmonic generation carried out at the Accelerator Test Facility at Brookhaven National Laboratory. A seed CO 2 laser at a wavelength of 10.6 mm was used to generate FEL output at a 5.3-mm wavelength. The duration of the output pulse was measured using a second-harmonic intensity autocorrelator, and the coherence length was measured using an interferometer. We also measured the energy distribution of the electron beam after it exited the second undulator, observing behavior consistent with that is expected at saturation. The intensity of the harmonic components of the output at 2.65 and 1.77 mm was determined relative to that of the 5.3-mm fundamental. Finally, using a corrector magnet upstream of the radiator, steering effects on the trajectories of the electron and light beams were studied. r 2001 Elsevier Science B.V. All rights reserved.
Nuclear Instruments and Methods in Physics Research A. 01/2001; 4752555(42):260-26565.
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A. Murokh,
C. Pellegrini,
J. Rosenzweig,
P. Frigola,
P. Musumeci,
A. Tremaine,
M. Babzien,
I. Ben-Zvi, A. Doyuran,
E. Johnson,
J. Skaritka,
X.J. Wang,
K.A. Van Bibber,
J.M. Hill,
G.P. Le Sage,
D. Nguyen,
M. Cornacchia
[show abstract]
[hide abstract]
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
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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T Shaftan, A Doyuran,
E Johnson,
S Krinsky,
H Loos,
J B Murphy,
G Rakowsky,
J Rose,
B Sheehy,
J Skaritka,
X J Wang,
Z Wu,
L H Yu
[show abstract]
[hide abstract]
ABSTRACT: High-gain Free Electron Lasers (FELs) are being developed to serve as short-wavelength, tunable, high-brightness radiation sources for advanced user applications. The widely studied approach in the high-gain FELs is known as self-amplified spontaneous emission (SASE) [1,2]. The SASE FEL delivers radiation pulses with high peak power and tuneable central wavelength. However, the output in general has limited temporal coherence and chaotic shot-to-shot intensity fluctuations. An alternative scheme is seeded harmonic generation, which is capable of producing temporally coherent pulses. We begin this paper with a review of several high-gain FEL schemes, which utilize electron beam, premodulated by an external radiation source. In such a scheme the FEL process does not take off from noise, as in the SASE case, but from beam bunched coherently. This ensures stable central wavelength, narrow bandwidth and small pulse-to-pulse energy fluctuations of the output. As an example of seeded FEL operation we present recent experimental results of the DUV FEL (BNL) [3]. At DUV FEL an 800 nm seed is used to produce saturated radiation at the third harmonic (266 nm). The third-harmonic of FEL output at 88 nm has been used in an ion pair imaging experiment in chemical physics as one of the first user application of seeded HG FEL [4].
