Author/Authors :
Yamazaki، نويسنده , , T. and Yamada، نويسنده , , K. and Sei، نويسنده , , N. and Ohgaki، نويسنده , , H. and Sugiyama، نويسنده , , S. and Mikado، نويسنده , , T. Uchikoshi T. S. Suzuki Y. Sakka، نويسنده , , R. and Noguchi، نويسنده , , T. and Chiwaki، نويسنده , , M. and Ohdaira، نويسنده , , T. and Kawai، نويسنده , , M. and Yokoyama، نويسنده , , M. and Hamada، نويسنده , , S. and Iwata، نويسنده , , A.، نويسنده ,
Abstract :
Lasing at around 352 nm of the NIJI-IV storage-ring free-electron laser (FEL) was successfully achieved in April 1994, and the tunable wavelength region of the system is now 350–595 nm. The electron-beam energy was 311 MeV, and the beam current was 6–10 mA/bunch. The peak output power was estimated roughly to be higher than 50 mW. After the first lasing at 595 nm and 488 nm with the present system in 1992, the storage ring NIJI-IV was modified to realize the lower-emittance mode, which proved to be quite effective for FEL experiments in the ultraviolet region. The radio-frequency knockout system has been modified to improve the purity of the single bunch. The gain of the 6.3-m optical klystron (ETLOK-II) is about 3.2 times that of a normal undulator of the same length. The optical cavity consists of dielectric multilayer mirrors made of Ta2O5/SiO2. The initial cavity loss was about 5 × 10−4, but it increased rapidly with ultraviolet and vacuum-ultraviolet irradiation.
