CW MEASUREMENTS OF CORNELL LLRF SYSTEM AT HOBICAT

In Energy Recovery Linacs, such as the Cornell ERL or BERLinPro, the main linac cavities are operated CW at low beam-loading. The choice of the external Q is given by two competing factors: The achievable field stability and the maximum provided RF power. To determine the optimum external Q, LLRF measurements with the Cornell system were performed at HoBiCaT to study the field stability at given microphonics detuning of a TESLA cavity for different gain settings and external Q values. Stable operation at external Q up to 2·10 8 was demonstrated at a field phase stability of 0.02 degrees.