Design of Cryogenic Control System for the Superconducting Module of the Injection Unit in the SHINE Tunnel

As the largest cryogenic superconducting platform in China and even Asia, the Shanghai High-intensity Ultrafast X-ray Facility (SHINE) highly depends on the stable operation of 1.3 GHz superconducting accelerating modules in a 2 K superfluid helium environment. This paper elaborates on the key control technologies developed and successfully applied to ensure the smooth aging process of superconducting modules in the cryogenic experiments of the SHINE injector section. To address the issue of thermal load fluctuations caused by the dynamic changes in RF power during the aging process, a dynamic power compensation algorithm based on real-time cavity pressure feedback was proposed and implemented. Meanwhile, a multi-variable coupled PID control strategy was adopted to achieve high-precision stability of the helium tank liquid level (±1%) and cavity pressure (±10 Pa). Experimental results show that this integrated control scheme effectively suppresses the risk of quenching caused by thermal disturbances, significantly improving the aging efficiency and operational reliability of the superconducting modules. This lays a solid technical foundation for the commissioning and long-term stable operation of the superconducting systems of SHINE and similar large-scale scientific facilities.