Enhancements of Machine Reliability and Beam Quality in Spring-8 Linac for Top-Up Injection into Two Storage Rings

The SPring-8 linac has been improved to realize stable top-up injection into the SPring-8 and the NewSUBARU storage rings. The beam energy instability of 0.02% rms in the long term was achieved by the following stabilizations: RF amplitude and phase stabilization, synchronization of beam timing and linac´s 2856 MHz RF, and the installation of an energy compensation system (ECS). Beam feedback controls compensate for residual long-term variation of beam trajectory and energy. A beam deflector installed between a gun and a prebuncher reduces gun´s dark currents, which spoil the purity of the stored beam in the storage ring.