一种压强稳定的多级真空差分系统

Highly Stable Pressure Produced by Multistage Differential Pumping Unit

上海光源软X射线自由电子激光器光束线主要用于X射线的传输与诊断,为了减少光子吸收,其传输环境须为无窗洁净的超高真空系统。气体通量衰减器和气体探测器是光束线诊断区域的关键设备,二者均需要充入一定量的气体,且工作精度依赖于气体压强的稳定度。文中介绍了一种具有压强反馈调节功能的多级真空差分系统直接过渡至其他超高真空设备,可在2.5 m内实现7个量级以上的差分比。

A novel type of the windowless differential pumping system,directly connected to the beamline of Shanghai soft X-ray free electron laser test facility,was developed for the purpose of X-ray transmission and diagno-sis.The new three-stage differential pumping system comprises three turbomolecular vacuum pumps,two long tubes, and a pressure regulation and feedback control unit.The properties of the newly-developed differential pumping sys-tem were experimentally evaluated.The test results show that the differential pumping system is capable of regularly achieving a pressure differential of over 7 orders of magnitude in 2.5 m long gas flow-path,and of producing a pres-sure of 80 Pa with a discrepancy below ±0.08% for the gas attenuator,and a pressure of 5 .3 ×10 -2 Pa with a fluctuation below ±1%for the gas monitor detector.