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| TUCAU01 |
FELs and High-energy Electron Cooling
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- Y. S. Derbenev
Jefferson Lab, Newport News, Virginia
- V. Litvinenko
BNL, Upton, Long Island, New York
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Electron cooling is extremely successful in cooling low and medium energy ions, including protons. ERLs are promising to extend the reach of traditional electron cooling to about 100 GeV/nucleon for heavy ions. Nevertheless, cooling of protons with energies from about 100 GeV (RHIC) to few TeV (LHC) becoming very complicated or even possible. Optical stochastic cooling [1] has potential to be an instrument of choice, but it has two main shortcomings: a) it requires significant modifications of the lattices of hadron machine and b) in the case of the protons it suffers from very inefficient interaction (radiation) of protons with TEM wave. It was suggested [2] to combine advantages of electrostatic interaction with broad-band FEL-amplifier in what is now called stochastic electron cooling. Such system will naturally fit into a straight section of modern high energy hadron colliders. In this paper we present description of the cooling process and give examples of FEL-based electron cooler for protons in RHIC and LHC. [1] A. Mikhalichenko and M. Zolotorev, Phys. Rev. Lett., 71, p.4146 (1993). [2] Ya. S. Derbenev, NIM A441 (2000) 223
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Slides
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| TUCAU02 |
Even Harmonic Generation on UVSOR-II Storage Ring
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- M.-E. Couprie
SOLEIL, Gif-sur-Yvette
- M. Hosaka
Nagoya University, Nagoya
- M. Katoh, A. Mochihashi, M. Shimada
UVSOR, Okazaki
- G. Lambert
RIKEN Spring-8, Hyogo
- M. Labat
CEA, Gif-sur-Yvette
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In the Coherent Harmonic Generation Free Electron Laser configuration, the electrons act as a non-linear medium radiating harmonics of a seed source (e.g., a laser). In the two-step seeding scheme, the seed field forces an energy modulation on the electron bunch in a modulator, converted into a density modulation as the electron beam travels through a dispersive section. Finally, in the radiator, the microbunched electron beam can emit coherently at the fundamental and the harmonics of the seed source. In this paper, successful even harmonic generation is reported on the CHG UV-FEL of UVSOR-II storage ring (Japan) at 600 MeV, using a 2.5 mJ, 1 kHz, 1.2 ps Ti:Sa laser at 800 nm. Second and fourth harmonics were generated using planar configuration of the undulators, and second harmonic was generated in helical configuration, in addition to already observed and studied third coherent harmonic. Such preliminary results allow attractive perspectives to understand further even harmonic generation process, still discussed among the FEL community: in single pass non-guided FELs, with planar undulators even harmonics are expected to vanish on-axis, a spectral selection that could be avoided with helical undulators.
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Slides
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| TUCAU03 |
Seeded Harmonic Generation with the Elettra Storage-Ring Free Electron Laser
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- E. Allaria, M. B. Danailov, G. De Ninno, B. Diviacco, E. Karantzoulis, C. Spezzani, S. Tileva, M. Trovo, F. Curbis
ELETTRA, Basovizza, Trieste
- M. Coreno
CNR - IMIP, Trieste
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We have recently demonstrated that the Elettra storage-ring free-electron laser is well suited for producing intense VUV harmonic radiation in seeded "single-pass" configuration. After reviewing the experimental setup, we present here the temporal and spectral characterization of the harmonic pulse with respect to several adjustable parameters, such as the seed power, repetition rate (10 Hz ± 1 kHz) and pulse duration, the seed pulse-electron bunch temporal detuning and the strength of the dispersive section between undulators. Measured peak power in the working wavelength range (i.e., 260-130 nm for the reported experiments) is several orders of magnitude above spontaneous synchrotron radiation. We also show that measurements are in very good agreement with 3D numerical simulations. The obtained results make the Elettra storage-ring free-electron laser in seeded "single-pass" configuration an ideal test facility for next generation linac-based FELs and, at the same time, a ready-to-use light source for user experiments.
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| TUCAU04 |
A Versatile High Gain Storage Ring FEL Powered by a Distributed Optical Klystron
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- J. Li, S. F. Mikhailov, V. Popov, Y. K. Wu
FEL/Duke University, Durham, North Carolina
- N. Vinokurov
BINP SB RAS, Novosibirsk
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In this work, we report the recent research results of a distributed optical klystron based storage ring FEL at Duke University, the DOK-1 FEL. The DOK-1 FEL is a hybrid system, comprised of four wigglers: two horizontal and two helical. This new FEL has demonstrated the highest FEL gain among storage ring based FEL oscillators using the distributed optical klystron configuration. The enhanced FEL gain of the DOK-1 FEL opens the door for storage ring based FELs to operate in the VUV region toward 150 nm. We have also realized controlled polarization switches of the FEL beam by a non-optical means through the manipulation of a buncher magnet. The DOK-1 FEL is a promising light source capable of rapid polarization switch in UV and VUV. The versatility of the DOK-1 FEL extends to many areas, including the ability of being operated as a multi-color light source for generation of coherent harmonic radiation.
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Slides
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