A New Kicker for the TLS Longitudinal Feedback System

A new longitudinal kicker will be installed into the Taiwan Light Source (TLS) storage ring in the near future. This kicker is part of the new bunch-by-bunch longitudinal feedback system for stabilization of beam dipole-mode longitudinal coupled-bunch instability in the ring. It will serve to provide fast switching kick voltage to each bunch at 500 MHz bunch crossing frequency. This new kicker employed the Swiss Light Source design with modifications on beam pipe geometry. It has been fabricated, baked out and vacuum tested by FMB-Berlin recently. The kicker has been delivered to NSRRC in November 2004. Longitudinal coupling impedance has been measured in house by coaxial wire method with resistive matching networks at input and output ports. The measured peak coupling impedance of the accelerating mode is 684 Ω with FWHM bandwidth at 280 MHz. It corresponds to a shunt impedance of 1368 Ω at centre frequency. These results agree very well with those calculated by GdfidL.