Progress of the longitudinal feedback system and associated beam observations in TLS

A digital feedback control system against longitudinal coupled-bunch instability is being developed for the Taiwan Light Source (TLS). This system is designed to stabilize bunch-phase oscillation of each of the 200 electron bunches in the TLS storage ring, and it operates at a bunch crossing frequency of 500 MHz. Two innovative aspects of this system are: (1) the special design of the digital signal processing (DSP) electronics, which run at a peak data rate of 500 Mbytes per second, and (2) the compact broadband longitudinal kicker for bunch-phase correction. Recent progress of this work and preliminary results of associated observations of beam longitudinal-dynamics will also be reported.