The Shanghai high repetition rate X-ray free electron laser (XFEL) and extreme light facility (SHINE), a quasi-continuous wave hard XFEL facility, is currently under construction. In order to test all the superconducting components, assembled cryomodules and undulators, the SHINE test facility that consists of various test benches has been built. A superfluid cryoplant with 1 kW@2K from Air Liquide Advanced Technologies (ALAT) was installed, commissioned, acceptance tested and turned into operation to support the cryogenic tests. The plant consists not only of a standard compressor system and cold box but also of a process vacuum system for 2 K operation. In the 2 K cryogenic system, a three-stage cold compressors are firstly used to compress helium vapor at a mass flow of up to 50 g/s from 28 mbar to about 400 mbar. Afterwards, the sub-atmospheric helium are continually pressurize to the suction pressure of the warm compressors by five parallel process vacuum pumps. During the first eight months of 2 K operations, the tuning of the cold compressor regulation has been implemented to adapt the different static and dynamic heat loads. A helium pressure stability of superconducting cavities better than ±0.15 mbar at 31 mbar was achieved inside the vertical test bench with additional heating power of 160 W. In this paper, the pump down procedure and the operation results of cryogenic system at 2 K will be described.

上海高重复率X射线自由电子激光器（XFEL）和准连续波硬XFEL设施（SHINE）目前正在建设中。为了测试所有超导组件、组装的低温模块和波荡器，建造了由各种测试台组成的 SHINE 测试设施。液化空气先进技术公司 (ALAT) 的 1 kW@2K 超流体低温装置已安装、调试、验收测试并投入运行，以支持低温测试。该工厂不仅由标准压缩机系统和冷箱组成，还包括用于 2 K 操作的工艺真空系统。在2 K低温系统中，首先使用三级冷压缩机将氦蒸气以高达50 g/s的质量流量从28 mbar压缩至约400 mbar。然后，低于大气压的氦气通过五个并联过程真空泵持续加压至温压缩机的吸入压力。在 2 K 运行的前八个月中，对冷压缩机调节进行了调整，以适应不同的静态和动态热负荷。在附加加热功率为 160 W 的立式试验台内，超导腔在 31 mbar 时的氦气压力稳定性优于 ±0.15 mbar。本文将介绍低温系统在 2 K 下的抽气过程和运行结果。描述。