RIKEN/SPring-8, Hyogo
The compact XFEL facility under construction in the SPring-8 campus aims at generation of SASE based XFEL at the wavelength of ~0.1 nm in 2010. Toward the smooth completion of the beam commissioning and achieving the reliable SASE XFEL operation, it is critically important to suppress the dark current upstream of the accelerator as much as possible. We thus investigated a removal scheme of the spatially diverged and energy deviated electrons forming the dark current by using sextupole magnets, which are installed over the C-band accelerating structures. The beam simulation showed that the combination of the distributed sextupole magnets with a small chicane, which locates in the adequate middle of the C-band accelerating structures, could efficiently remove the dark current emitted from the C-band acceleration structures. Here, we present the simulation results and the dark current suppression scheme designed for the compact XFEL facility at SPring-8.
RIKEN/SPring-8, Hyogo
JASRI/SPring-8, Hyogo-ken
The SPring-8 compact SASE source (SCSS) test accelerator was constructed in FY2005 to demonstrate a new concept for X-ray free electron lasers composed of a low-emittance thermionic electron injector, a high-gradient normal conducting C-band accelerator, and a short-period in-vacuum undulator. With a 250 MeV electron beam, continuous SASE saturation can generate intense and stable FEL beams at the wavelength range from 50 to 60 nm with the maximum pulse energy of 30 micro-J and the intensity fluctuation of ~10%. Analysis of the SASE saturation data with a 3D-FEL simulation code suggests negligible degradation of the electron beam emittance during the high bunch compression process. We also succeeded in operating the C-band accelerator with a high accelerating gradient of 37 MV/m and a repetition rate of 60 pps. Now, the FEL beam is routinely delivered for user experiments. At this conference we will present the machine performance and recent progress of the SCSS test accelerator together with the anticipated performance of the 8 GeV XFEL under construction.
