12kW@2K Helium Cryogenic Control System Design

This paper presents the design and implementation of a 12kW@2K supercritical helium cryogenic control system for the Shanghai Hard X-ray Free Electron Laser Facility (SHINE). The system provides a stable cryogenic environment for 56 standard 1.3 GHz superconducting modules, meeting the stringent temperature control requirements of the accelerator for high-precision operation of superconducting cavities. A distributed PLC architecture integrated with EPICS is adopted, comprising three refrigerators, four distribution valve boxes, and 39 module subsystems. Redundant network design ensures reliable data transmission. Core functionalities include a four-stage automated cooling process (from 300 K to 2 K), dynamic power compensation, and a safety interlock mechanism.Experiments show that the system can stabilize the liquid level of the helium tank within ±1% and maintain the pressure at 3100Pa ± 10Pa, effectively ensuring the smooth progress of low-level experiments. Dynamic power compensation adjusts heater power in real time based on a model correlating cavity pressure with heat load, ensuring stability during cryogenic operation. The system has been successfully applied in the commissioning of the injector section, validating its efficiency and safety in providing a cryogenic environment for superconducting accelerators, and serving as a key technical foundation for the SHINE project.