| Paper |
Title |
Page |
| TUPMS033 |
Chicane Radiation Measurements with a Compressed Electron Beam at the BNL ATF
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1254 |
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- G. Andonian, R. B. Agustsson, A. M. Cook, M. P. Dunning, E. Hemsing, A. Y. Murokh, S. Reiche, J. B. Rosenzweig
UCLA, Los Angeles, California
- M. Babzien, K. Kusche, R. Malone, V. Yakimenko
BNL, Upton, Long Island, New York
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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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| TUPMS034 |
Seeded VISA: A 1064 nm Laser-Seeded FEL Amplifier at the BNL ATF
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1257 |
| |
- M. P. Dunning, G. Andonian, E. Hemsing, S. Reiche, J. B. Rosenzweig
UCLA, Los Angeles, California
- M. Babzien, V. Yakimenko
BNL, Upton, Long Island, New York
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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 at Brookhaven National Laboratory. The study is motivated by the demand for a short Rayleigh length FEL amplifier at 1 micron for high power transmission with minimal damage of transport optics. Planned measurements include transverse and longitudinal coherence, angular distribution, 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 emission angles and increase of the amplifier efficiency. Results of start-to-end simulations will be presented with preliminary experimental results.
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| TUPMS035 |
The FINDER Photoinjector
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1260 |
| |
- A. Fukasawa, H. Badakov, E. Hemsing, B. D. O'Shea, J. B. Rosenzweig
UCLA, Los Angeles, California
- S. G. Anderson
LLNL, Livermore, California
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The FINDER project at LLNL is an inverse-Compton scattering demonstration, aimed at creating MeV-class, narrow band photons for interrogation of nuclear materials. The requirements experiment requires a state-of-the-art photoinjector. Such a device is under development by a UCLA/LLNL collaboration. We report on a number of design innovations, such as photocathode gun RF symmetrization and large mode separation, which sets this device apart from previous generations of the BNL/SLAC/UCLA 1.6 cell gun. Measurements characterizing the RF photocathode gun and emittance compensation solenoid are presented.
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| TUPMS036 |
Characterization of Orbital Angular Momentum Modes in FEL Radiation
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1263 |
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- E. Hemsing, G. Andonian, J. B. Rosenzweig
UCLA, Los Angeles, California
- M. Babzien, V. Yakimenko
BNL, Upton, Long Island, New York
- A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv
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Optical guiding of the radiation pulse through the source electron bunch in a free-electron laser is a well known phenomena that suppresses diffraction of the output radiation, and thus enhances the gain. The resulting radiation can be described by an expansion of orthogonal modes that are also composed of eigenstates of orbital angular momentum (OAM). In the VISA-FEL experiment at the ATF-BNL, gain guiding has been observed under self-amplified spontaneous emission conditions at 840 nm with a strongly chirped input electron beam. The resulting far-field transverse radiation profiles are observed to contain multiple modes in the angular intensity spectrum, and exhibit both hollow and spiral structures characteristic of single or multiply interfering OAM modes. Current efforts to characterize the transverse radiation profile both experimentally and through start-to-end simulations are presented.
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