RHIC 28 MHz accelerating cavity system

The 28 MHz accelerating system consists of a quarter wave cavity driven by an inductively coupled 100 kW tetrode amplifer and 1 kW solid state driver amplifer. 40 dB of RF feedback closed around the cavity and amplifiers reduces small perturbations within the loop by a factor of 100, and reduces the time required to shift the phase at transition by a factor of 10, limited by the saturation of the drive chain. The cavity is tuned over a 200 kHz range by a mechanical tuner which varies the gap capacitance. Broadband HOM damping is provided by two orthogonal loop coupled high pass filters. Design parameters and commissioning results are presented.