超导铌材低温表面气体吸附实验研究  

Cryogenic Surface Adsorption and Desorption of Superconductive Niobium: An Experimental Study

作　　者：胡传飞[1,2] 李春龙[1] 白峰[1,2] 宋玉堃 赵玉刚[1] 张军辉[1] 

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]中国科学院大学,北京100049

出　　处：《真空科学与技术学报》2017年第8期760-765,共6页Chinese Journal of Vacuum Science and Technology

基　　金：国家自然科学基金资助项目(91426303)

摘　　要：超导直线加速器中超导腔等低温表面在吸附气体后会对其工作性能及稳定性产生恶劣影响。为了提高超导加速器性能和稳定性,文中搭建了一套实验平台,将样品腔降温至极低温4 K,并通过等温吸附实验,研究了铌材低温表面对氢气等不同气体的吸附过程。文中给出了一定表面处理工艺及温度下吸附能力和吸附过程压力与吸附量关系以及氢气饱和蒸气压等实验结果,并与相关参考文献数据进行了比较。实验结果表明:在超导直线加速器中,氢气、氦气饱和蒸气压远高于其运行允许值;在极低温条件下,如4 K,在吸附过程中吸附量决定了真空压力大小,而非真空压力大小决定吸附量;极低温真空管路内由于气体传输或泄露时,实际测得压力上升存在一定的时间延后,延后时长与气体种类、温度及管线几何结构均有着密切关系。Here,we experimentally addressed the problem that the gases,adsorbed on cryogenic surfaces of the niobium sample cavity,seriously affect the performance and stability of superconductive linear accelerator（ LINAC）. The impact of the cryogenic adsorption of H_2 and He on the pressure was investigated with the lab-built testplatform capable of cooling the Nb sample cavity down to 4K and via literature search. The results include： i） the saturated vapor pressures of H_2 and He are much higher than the upper limits of superconductive LINAC; ii） at 4K,the gas coverage higher than one monolayer,significantly affects the pressure,and formation of one monolayer takes a long time;（ iii） a pressure rise,possibly due to gas transport and/or leakage of ultrahigh vacuum cryogenic pipeline,cannot be simultaneously measured and the delay depends on the gas-type,temperature and pipeline geometry.

关 键 词：真空与低温 低温吸附 实验研究 超导加速器 

分 类 号：TB716[一般工业技术—真空技术]