Full Energy Injection and Top-up Operation at UVSOR-II.

Top-up operation was successfully demonstrated at UVSOR-II, which will remove the short beam-lifetime problem caused by strong Touschek effect due to the small emittance, 27 nm-rad, and the low electron energy, 750 MeV. In these years, we have improved the accelerators, step by step, towards top-up operation. The radiation shielding wall was reconstructed. The energy of the booster synchrotron and the beam transport line were successfully upgraded from 600 MeV to 750 MeV, by replacing the magnet power supplies in 2006. Soon after, we succeeded in injecting the electron beam at the full energy. We improved the radiation safety system and constructed a injection control system. In autumn, 2008, we succeeded in operating the ring for 12 hours as keeping the beam current quasi-constant at 300 mA. Currently, we operated the ring in the top-up mode for 12 hours on every Thursday night, to check the effects on the users’ experiments. In 2009, we have succeeded in the top-up operation in single bunch mode. Free electron laser oscillation with the top-up mode was also successfully demonstrated. [ABSTRACT FROM AUTHOR]