Stable operation of a self-amplified spontaneous-emission free-electron laser in the extremely ultraviolet region

• Main Authors: Tsumoru Shintake, Hitoshi Tanaka, Toru Hara, Takashi Tanaka, Kazuaki Togawa, Makina Yabashi, Yuji Otake, Yoshihiro Asano, Toru Fukui, Teruaki Hasegawa, Atsushi Higashiya, Naoyasu Hosoda, Takahiro Inagaki, Shinobu Inoue, Yujong Kim, Masanobu Kitamura, Noritaka Kumagai, Hirokazu Maesaka, Sakuo Matsui, Mitsuru Nagasono, Takashi Ohshima, Tatsuyuki Sakurai, Kenji Tamasaku, Yoshihito Tanaka, Takanori Tanikawa, Tadashi Togashi, Shukui Wu, Hideo Kitamura, Tetsuya Ishikawa, Takao Asaka, Teruhiko Bizen, Shunji Goto, Toko Hirono, Miho Ishii, Hiroaki Kimura, Toshiaki Kobayashi, Takemasa Masuda, Tomohiro Matsushita, Xavier Maréchal, Haruhiko Ohashi, Toru Ohata, Katsutoshi Shirasawa, Tetsuya Takagi, Sunao Takahashi, Masao Takeuchi, Ryotaro Tanaka, Akihiro Yamashita, Kenichi Yanagida, Chao Zhang
• Format: Article
• Language: English
• Published: American Physical Society 2009-07-01
• Series: Physical Review Special Topics. Accelerators and Beams
• Online Access: http://doi.org/10.1103/PhysRevSTAB.12.070701

We achieved stable operation of a free-electron laser (FEL) based on the self-amplified spontaneous-emission (SASE) scheme at the SPring-8 Compact SASE Source (SCSS) test accelerator in the extremely ultraviolet region. Saturation of the SASE FEL power has been achieved at wavelengths ranging from 50 to 60 nm. The pulse energy has reached ∼30  μJ at 60 nm. The observed fluctuation of the pulse energy is about 10% (standard deviation) for several hours, which agrees with the expectation from the SASE theory showing the stable operation of the accelerator. The SASE FEL has been routinely operated to provide photon beams for user experiments over a period of a few weeks. Analysis on the experimental data gave the normalized-slice emittance at the lasing part is around 0.7π   mm mrad. This result indicates that the normalized-slice emittance of the initial electron beam, 0.6π   mm mrad in a 90% core part, is kept almost unchanged after the bunch compression process with a compression factor of approximately 300. The success of the SCSS test accelerator strongly encourages the realization of a compact XFEL source.