Suppression of longitudinal coupled-bunch instabilities at the KEK-PF

A bunch-by-bunch feedback system has been developed to suppress longitudinal coupled-bunch instabilities at the KEK-PF. A longitudinal kicker based on a DAFNE-type overdamped cavity has been designed and installed in the ring, and a general purpose signal processor, called iGp, has been developed by the collaboration of the KEK, SLAC, and INFN-LNF. The entire feedback loop has been closed by the end of June 2007. and the feedback system has successfully suppressed the longitudinal dipole-mode instabilities up to 450 mA, which is a nominal operating beam current at the PF.