Femto-second X-ray generation by the tera-watt laser slice method in the SPring-8 storage ring

Abstract

Feasibility study of the generation of ultra-short pulse X-rays in the SPring-8 storage ring with a laser slice method is discussed. The electron beam energy is modulated by applying a tera-watt laser with a length of 100 fs in parallel to the electron beam running through a wiggler. Pulsed X-rays, emitted from a bending magnet, are separated from the X-rays due to the beam bunch with a slit. Parameters of the system are optimized based on a formalism with respect to the laser beam interaction in a wiggler, beam dynamics and laser beam optics. Numerical calculations of the interaction are carried out taking into account a Gaussian distribution of electron and laser beams. The expected flux is 8.1×10 4 photons/s/mrad/0.1% bandwidth at a bunch beam current of 10 mA with a pulse length of 240 fs in full width. If the lattice functions are modified such that an undulator is used as a radiator in a negative dispersion section, we can expect the pulsed X-rays with a flux of 2.9×10 7 photons/s/0.1% bw and a pulse length 180 fs. Because of a high beam energy of 8 GeV, a very high laser field is required, which induces limitations in the laser beam optics. Discussions are extended to the New SUBARU storage ring of 1.5 GeV.