Tuner control in TRIUMF ISAC 2 superconducting RF system

The TRIUMF ISAC 2 superconducting RF system operates in self-excited, phase locking mode. A mechanical tuner is used to minimize the required RF power. The tuner derives the tuning information from the phase shift around the self-excited loop. Its accuracy is however reduced by phase drift in amplifiers and cables due to thermal effects. The cross product between the amplitude and the phase errors is used to detect this drift. The signal derived from the cross product does not depend on any initial value adjustment. Furthermore, no special adjustment is required and the measurement can be performed online during beam production.