Speaker
Description
Large-scale superconducting linear accelerators such as HIAF operate nearly a hundred SRF cavities, whose operation is constrained by slow array startup, Lorentz-force-induced dynamic detuning under pulsed beam, and manual fault recovery. This work presents an integrated automatic loading, online monitoring, and rapid recovery method for the low-level radio frequency (LLRF) system. A distributed multi-process architecture is adopted, with an independent process and a seven-state finite-state machine per cavity, standardizing the sequence from open-loop preloading, amplitude-loop locking, and automatic frequency tuning to phase-loop closure. In pulsed mode, the dynamic detuning is identified online from the pulse waveforms and used to drive pulse-to-pulse mechanical tuning. Faults such as cavity-voltage collapse, quench, and severe detuning are detected by multi-parameter criteria; event-driven hierarchical interlock reset, combined with backfilling of historical steady-state parameters, rebuilds the full closed loop without manual intervention. The system has been deployed on all 96 cavities (17 cryomodules) of HIAF: a single global command loads the entire array in about 5 min, compared with about 120 min manually. In a 10 h parallel run on 81 cavities (about 5.83×10⁵ samples), the median amplitude and phase stabilities reached 0.023% and 0.033°, with 100% closed-loop retention, a roughly 95% automatic recovery success rate, and a mean recovery time of about 45 s versus about 5 min for manual recovery.
