Oh, J-O.

Paper	Title	Page
TU201	The KEK C-Band RF System for a Linear Collider	256
	H. Matsumoto, S. Takeda, S.S. Win, M. Yoshida KEK, Ibaraki H. Baba, T. Shintake RIKEN Spring-8 Harima, Hyogo J-O. Oh PAL, Pohang
	The C-band (5712 MHz) main linac has been developed just motivated by the urgent and essential physics program at the e+e- linear collider. In total ~8000 accelerating structures and ~4000 klystrons with modulators are needed for 500 GeV C.M. energy. Therefore these units have to meet strict requirements for: high reliability, simplicity, easy operation, reasonable power efficiency and low cost. This list provides a guiding principle and the boundary conditions for our design work. We have already developed the conventional and PPM type 50 MW class C-band klystrons, modulators, and HOM-free accelerator structures. The first high power an rf compressor cavity made of a low thermal expansion material was designed to provide stable operation even with a very high Q of 200 k, it was successfully operated an output rf power of 135 MW at KEK. The C-band linac rf-system will be used for the SASE-FEL project at SPring-8, but it will also serve to verify the design and components, which can eventually be deployed for the main linac rf system in a future linear collider.
	Transparencies
WE204	PAL Linac Upgrade for a 1-3 Å XFEL	544
	J-O. Oh, W. Namkung POSTECH, Pohang, Kyungbuk Y. Kim DESY, Hamburg
	With the successful SASE FEL saturation at 80 nm wavelength at TTF1, TTF2 will begin re-commissioning in the fall of 2004 as an FEL user facility to 6 nm with 1 GeV beams. The high gain harmonic generation is also confirmed by the DUV-FEL experiments at 266 nm with seeding wavelength at 800 nm. In order to realize a hard X-ray SASE FEL (SASE XFEL) with a lower energy beams, we need a long in-vacuum mini-gap undulator and a GeV-scale FEL driving linac that can supply an extremely low slice emittance, a high peak current, and an extremely low slice energy spread. PAL is operating a 2.5 GeV electron linac as a full-energy injector to the PLS storage ring. By adding an RF photo-cathode gun, two bunch compressors, and a 0.5 GeV S-band injector linac to the existing PLS linac, and by installing a 60 m long in-vacuum undulator, the PLS linac can be converted to a SASE XFEL facility (PAL XFEL) which supplies coherent X-ray down to 0.3 nm wavelength. The third harmonic enhancement technique can supply coherent hard X-ray beams to 0.1 nm. The technical parameters related to these goals are examined, and preliminary design details are reviewed for the PAL linac upgrade idea for a 1-3 Å PAL XFEL.
	Transparencies