Stable Operation of the 2 K Cryogenic System for the Superconducting Accelerator at Peking University

A superconducting energy recovery linac test facility (PKU-SETF) was built at Peking University, and a 2 K cryogenic system, which is the first closed-loop 2 K cryogenic system for a superconducting accelerator in China, was constructed for the 1.3 GHz 3+1/2 cell dc-SRF injector. The main accelerator consists of two nine-cell TESLA-type superconducting cavities of the PKU-SETF. The commissioning and stable operation of this 2 K cryogenic system was carried out. A helium pressure stability of better than +/- 0.1 mbar and a total refrigeration capacity of 65 W at a temperature of 2 K was reached.