Low-level RF control system issues for an ADTT accelerator

The RF control system for a charged‐particle accelerator must maintain the correct amplitude and phase of the RF field inside the accelerator cavity in the presence of perturbations, noises, and time varying system components. For an accelerator with heavy beam‐loading, fluctuations in the beam current cause large perturbations to the RF field amplitude and phase that must be corrected by the RF control system. The ADTT applications require a high‐current, heavily beam‐loaded, continuous‐wave (CW) accelerator. Additional concerns created by the CW operation include system start‐up, beam interruption, and fault recovery. Also, the RF control system for an ADTT facility must include sophisticated automation to reduce the operator interaction and support. This paper describes an RF control system design that addresses these various issues by evaluation a combination of feedback and feedforward control techniques. Experience from the high‐current Ground Test Accelerator (GTA) is drawn upon for this RF control...