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WEOB03 |
Laser-induced CSR : Seeding of the Microbunching Instability in Storage Rings |
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- E. Roussel, S. Bielawski, C. Evain, C. Szwaj, T. Tanikawa
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
- M. Adachi, M. Katoh
UVSOR, Okazaki, Japan
- M. Hosaka, N. Yamamoto
Nagoya University, Nagoya, Japan
- M. Le Parquier
CERLA, Villeneuve d'Ascq, France
- H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan
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Microbunching instability arises both in Linear Free Electron Laser and in storage rings due to the interaction of the electrons with their own radiation, mainly in dipoles (bending magnets in storage rings and chicanes in linear FEL). This instability leads to the formation of micro-structures in the longitudinal phase-space (typically in the mm range in the longitudinal profile) and limits the performances of these accelerator based ligth sources. We show that the interaction of the electron bunch with an external laser pulse, whose envelope is modulated at a Terahertz frequency (associated to mm wavelength), allows to investigate the dynamics of electron bunches in storage rings during the micro-bunching instability. Here, we achieve experiments at UVSOR-II* around the CSR instability threshold. We also perform numerical calculations using a one-dimensional Fokker-Planck-Vlasov modeling taking into account CSR wakefield. This seeding mechanism highlights that CSR depends on the wakefields for some ranges of excited wavenumber.
* C. Evain et al., Phys. Rev. ST Accel. Beams 13, 090703 (2010); S. Bielawski et al., Nature Physics 4, 390 (2008).
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Slides WEOB03 [2.523 MB]
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| WEPD41 |
Construction and Commissioning of Coherent Light Source Experiment Station at UVSOR |
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- S. Tanaka, M. Adachi, K. Hayashi, M. Katoh, S.I. Kimura, E. Nakamura, J. Yamazaki
UVSOR, Okazaki, Japan
- M. Hosaka, Y. Taira, Y. Takashima, N. Yamamoto
Nagoya University, Nagoya, Japan
- T. Takahashi
Kyoto University, Research Reactor Institute, Osaka, Japan
- H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan
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At UVSOR, Coherent light source technologies, such as resonator free electron laser, coherent harmonic generation and coherent synchrotron radiation via laser modulation, have been developed parasitically by using an undulator and a beam-line normally used for photo-electron spectroscopy. Under Quantum Beam Technology Program of MEXT in Japan, we started constructing a new experiment station dedicated for the coherent light source developments. We created a new straight section by moving the injection line. Two identical undulators 1m long were constructed and installed there. A buncher magnet was constructed and installed between the undulators to form an optical klystron. Two beam-lines, BL1U and BL1B, were constructed, the former of which is for free electron laser and coherent harmonic generation and the later for the coherent synchrotron radiation in the terahertz range. The laser system was reinforced and new laser transport line was constructed. The generation of coherent synchrotron radiation by laser modulation was already tested. The construction of the optical cavity for the free electron laser will start in this year.
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