基于4 K制冷机的低温泵抽气单元性能分析

Performance Analysis of Pumping Units of Cryopump Based on 4 K Cryocooler

中性束注入实验单元系统调试和小尺寸样机验证测试需要真空环境支持,针对实验气体负载性质与真空要求,探索研制外置式制冷机低温泵。设计了一种基于单台4 K制冷机的低温泵并开展抽气单元性能分析,采用ANSYS热分析方法研究抽气单元热学性能,得到了不同气体热负载下的温度分布,结果表明,抽气面温度处于5 K左右,能够有效抽除H_(2)、He等难凝性气体。采用MOLFLOW对连接抽速测试系统的低温泵进行了气体粒子运动模拟,验证了抽气单元设计的合理性,并模拟得到气体捕获系数为0.409;探究了气体负载对抽气性能的影响,结果表明,受温升影响,泵的抽速波动较小,抽气性能良好。研究方法与结果为实验用制冷机低温泵的研制提供了有益参考。

In this paper,neutral beam injection experimental unit system debugging and small size prototype verification test need vacuum environment support,according to the experimental gas load properties and vacuum requirements,exploring the development of an external refrigerator cryogenic pump.A cryogenic pump based on a4 K cryocooler was designed,and the performance of the pumping unit was analyzed.ANSYS thermal analysis method was used to study the thermal performance of the pumping unit,and the temperature distribution under different gas thermal loads was obtained.The results showed that difficult-condensing gases such as H_(2)and He could be effectively extracted when the temperature of the pumping surface was about 5 K.MOLFLOW was used to simulate the gas particle movement of the cryogenic pump connected to the pumping speed test system,the rationality of the pumping unit design was verified,and the trapping coefficient was 0.409.The influence of gas load on the pumping performance is investigated.The results show that the pumping speed of the pump fluctuates less under the influence of temperature rise,and the pumping performance is superb.Research methods and results provide a useful reference for the development of cryopumps for the NBI experimental test.