Cavity Control System – Optimization Methods

The paper is an introduction to the optimization methods of the linear accelerator cavity control system. Three distinct time periods of cavity operation are considered; filling with the EM field energy, field stabilization for the accelerated beam, and field decay. These periods are considered as different states of the cavity corresponding to adequate solutions of differential equation modeling the cavity behavior. The cavity could be operated by several different methods in each work phase: During the filling – feedback and feed-forward alone, feedback and feed-forward together, self-tuning; During the flattop – feed-forward and feedback alone or together, During the decay – detuning and quality factor may be measured. The optimization is understood as a choice of the most efficient way of the cavity control during each period. The control may be done in terms of minimum power consumption from the klystron during whole work cycle and efficient field stabilization in the cavity, during flattop period. The introductory analysis of the cavity operational modes in three mentioned periods is presented in this paper. Additionally, the alternative, more precise algorithm of the cavity field detection is proposed. The cavity field is estimated as a result of intermediate frequency signal envelope decoding. All considerations in this paper deal with a single cavity system in noiseless and deterministic conditions.