Enhanced operational stability of the SSRF superconducting wiggler through dispersion modulation and orbit correction

Abstract The operational stability of the Shanghai Synchrotron Radiation Facility (SSRF) was severely challenged in late 2024 by 20 quench events in the 4.2 T Superconducting Wiggler (SCW). To address these quenches, a localized horizontal dispersion bump was established within the SCW straight section by rematching twenty quadrupole magnets. This lattice reconfiguration modulates the trajectories of off-momentum particles induced by RF cavity trips, thereby directing beam losses away from the superconducting coils and preventing localized energy deposition that triggers quenches. Beam-based measurements confirm that this optical modification effectively suppresses SCW quenches induced by RF interlocks. Furthermore, a complementary orbit compensation scheme was implemented to correct the closed-orbit distortions caused by residual magnetic field errors after SCW quenches. This measure reduced the beam recovery time from over four hours to less than one hour. Together, these integrated strategies have significantly enhanced the operational stability of the SCW and the overall reliability of the SSRF.