X-ray FEL project at SPring-8 Japan

In order to establish technology for future X-ray FEL at 1 Angstrom wavelength region, RIKEN/SPring-8 started SCSS-project[1] in 2002. It is a soft X-ray SASE FEL machine aiming at demonstrating FEL operation below 10 nm wavelength with 1 GeV electron beam. Using the short period in-vacuum undulator and the high gradient C-band main accelerator, the machine becomes compact, and fits within a 100 in long tunnel, so that it was named SCSS: Spring-8 Compact SASE Source. To saturate FEL within 25 in long undulator line, we need a high quality beam: r.m.s normalized emittance should be below 2 pi-mm-mrad (r.m.s normalized) with 2 kA peak current. To generate this beam, we are developing a HV pulse gun using thermionic cathode (CeB6 single crystal) and sub-harmonic buncher system. In 2003, we start beam test of HV gun and high power test of the C-band accelerator. The first FEL operation is scheduled in 2006 at 100-10 nm wavelength.