Design and development of the EAST plug-in cryopump for long-pulse high-performance operation

At present, the in-vessel cryopump of the EAST divertor demonstrates inadequate pumping performance during long-pulse high confinement mode (H-mode) plasma operations, and the disassembly and maintenance of this cryopump pose significant challenges. In response to these issues and considering the constraints of the installation space of the cryopump, an EAST plug-in cryopump have been developed based on cryoadsorption and cryocondensation principles. The plan is to install four plug-in cryopumps at different vertical ports of the EAST vacuum vessel. These cryopumps will operate in a staggered manner with a specific time interval to achieve a quasi-continuous pumping system. This paper provides a systematic discussion of the design, simulation analysis, and experimental studies of the plug-in cryopump to validate its feasibility for the EAST application. In conclusion, each individual cryopump exhibits an average pumping speed of approximately 9255 L/s for hydrogen, 7001 L/s for deuterium, and 5290 L/s for helium. The pumping capacity and regeneration time also meet the requirements of EAST experiments. Our ultimate goal is to achieve the long-pulse high-performance plasma operation in EAST with the support of the plug-in cryopumps, while also laying the foundation for the development of divertor cryopumps for future fusion reactors.