Application of disturbance observer-based control on pulsed superconducting radio frequency cavities

Abstract

A disturbance observer (DOB)-based control approach was verified using the low-level radio-frequency systems of superconducting (SC) cavities operated in a continuous wave (CW) mode in a compact energy recovery linac (cERL) at KEK. This approach compensates for both predictable and unpredictable disturbances in a radio frequency (rf) system such as beam loading, Lorentz force detuning, and microphonics. This paper generalizes the DOB method in pulsed SC rf systems in the cERL at KEK. The results show that the pulse-to-pulse stabilities of the rf system are improved as expected by using this control approach. Furthermore, this method is validated by successfully compensating long pulse beam-loading effects in cERL.