Speaker
Description
The China Spallation Neutron Source (CSNS) operates an 80-MeV linac and a 1.6-GeV rapid cycling synchrotron (RCS), routinely delivering beam power well above its original design value. Sustaining high beam availability under such conditions requires not only hardware maintenance but also physics-informed operational strategies. This contribution presents how the CSNS accelerator physics group maintains and restores beam performance through a layered approach combining procedure-based physics adjustments, Bayesian optimization (BO) assisted retuning, and machine protection. Two representative cases are discussed. In the first, degraded RF conditions in the drift-tube linac were compensated by re-optimizing the longitudinal parameters tied to the phase-space painting scheme, preserving RCS transmission until a hardware upgrade could be implemented. In the second, aperture-limited injection losses, previously mitigated by BO-based weekly beam recovery, were eliminated by an injection-region upgrade, retiring the corresponding recovery procedure. Building on this experience, prospects for online drift compensation using safety-constrained BO are outlined.