• N. Nishimori, R. Hajima, H. Iijima, R. Nagai
  JAEA/ERL, Ibaraki
• Y. Honda, T. Miyajima, T. Muto, M. Yamamoto
  KEK, Ibaraki
• M. Kuriki
  HU/AdSM, Higashi-Hiroshima
• M. Kuwahara, T. Nakanishi, S. Okumi
  Nagoya University, Nagoya

Energy recovery linac (ERL) based next generation light sources such as X-ray oscillator require high brightness electron gun. We have developed a 500-kV, 10-mA photocathode DC gun by the collaboration efforts of JAEA, KEK, Hiroshima Univ. and Nagoya Univ. A segmented cylindrical ceramic insulator with guard rings is employed to improve stability and robustness at high voltage operation by keeping secondary electrons away from the ceramic surface. A Cockcroft-Walton power supply is installed in a SF6 tank and high voltage test up to 550kV was successfully done. All the vacuum chambers are made of chmically polished titanium alloy with very low out-gassing. A photocathode preparation system was assembled and vacuum test is performed. Up-to-date status of the gun development will be presented in detail.

• R. Hajima, N. Nishimori
  JAEA/ERL, Ibaraki

In Japan, we have organized the ERL collaboration initiative towards future ERL light sources. Construction of an X-ray synchrotron light source, a multi-GeV ERL, is one of the targets of our collaboration. As an option of the multi-GeV ERL, we consider an X-ray FEL oscillator (XFEL-O) to produce hard X-ray pulses with excellent temporal coherence [1]. In this study, we present simulation results of the XFEL-O such as FEL lasing including spectral narrowing and nonlinear phase shift at Bragg reflectors, possible energy-doubling configuration to enhance the single-pass gain and so on.

[1] R. Hajima, N. Nishimori, "Free-Electron Laser Options for the Energy-Recvory Linac Light Source in Japan", MOPPH048, Proc. FEL'08.