RF CONTROL SYSTEMS FOR THE TRIUMF ISAC RF

The ISAC RF system consists of a radio frequency quadrupole accelerator, five drift tube LINACs, seven bunchers, a dual frequency chopper and a bunch rotator. With the exception of the prebuncher, which required a sawtooth waveform, the other cavities have cavity Q's in excess of 5000 and are either excited with the fundamental frequency of 35.36 MHz, with the third harmonic frequency of 106.08 MHz or with subharmonic frequencies of 5.893MHz and 11.786 MHz. All are running synchronously and are individually amplitude and phase regulated. A hybrid rf control system uses analogue components to provide front end rf detection and digital signal processors to provide closed-loop amplitude, phase and tuning control. A single feedback circuit is employed for each cavity. This system, as well as the frequency synthesis and distribution system, is described in this paper.