Author: Le Parquier, M.
Paper Title Page
WEOB03
 Laser-induced CSR : Seeding of the Microbunching Instability in Storage Rings  
 
  • 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
  
  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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