Concept design of cryogenic system for the high energy photon source at IHEP.

The High Energy Photon Source (HEPS) is scheduled to be put into operation in 2025 at Institute of High Energy Physics in China. A cryogenic system will support the demands of the HEPS, which includes a liquid helium plant and a closed-cycle liquid nitrogen plant. The preliminary conceptual design has been carried out. And the liquid helium plant will be consisted of a helium refrigerator on a capacity at 2000W@4.5K, a cryogenic distribution transfer system and helium recovery and purifaction system for 7 superconducting RF cavities in 7 cryostats. The cryostats will be installed in the main ring. The closed-cycle nitrogen plant will be constructed by distributing of liquid nitrogen and re-condensation nitrogen vapour system for 15 beamlines station and 7 thermal insulating shields and 9 cryogenic permanent magnets. Schematic diagram and recent development of the cryogenic system is described in this paper.