Booster and Main Accelerator Phase Detector System for Cavity Tuning

Each NAL booster and main accelerator rf station contains a phase lock control loop to resonate the beam-line cavities at the applied excitation (reference) frequency. The phase sensor in the loop is a dual channel phase detector having an octave bandwidth, an amplitude dynamic range of 60 dB, a phase balance vs. frequency better than ±2° and a zero crossover phase sensitivity of 0.18 V/deg. The phase detector develops a feedback "error" signal proportional to the phase difference between the rf reference signal and an rf signal representing the rf station beam line voltage. This paper discusses the rf cavity tuning feedback loop configuration and describes the details of the phase detector circuitry.