RF Phase Control System

A system for automatically controlling the instantaneous phase of the accelerating voltage at each of the six accelerating stations at the Cornell 12 GeV Electron Synchrotron has been developed. The phases are controlled to ±50° relative to a master oscillator. The system comprises electronic phase shifters to compensate for variations in klystron phase shifts during the acceleration cycle, and mechanical phase shifters to compensate for drive cable delay variations. Near full energy, when different klystron modulator waveforms are used in each station, the phase control provides an effective increase of 20% in RF power by cancelling the 180° phase shift which occurs in each klystron as it is brought up to full power. The phase control system is also a great aid in obtaining correct phasing when more than one station is used to pick up the beam.