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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。
Superconducting linear accelerator superconducting cavity and other low temperature surface in the adsorption of gas will have adverse effects on its performance and stability. In order to improve the performance and stability of the superconducting accelerator, a set of experimental platform was set up to cool the sample chamber to extremely low temperature 4 K and the adsorption process of different gases such as hydrogen on the low temperature surface of niobium material was studied by isothermal adsorption experiments. In this paper, the experimental results of certain surface treatment process and temperature adsorption capacity, adsorption pressure and adsorption capacity and hydrogen saturation vapor pressure are given, and compared with the relevant reference data. The experimental results show that the saturated vapor pressure of hydrogen and helium in superconducting linear accelerator is much higher than the allowable value of its operation. At very low temperature, such as 4 K, the adsorption amount determines the vacuum pressure in adsorption process, The amount of vacuum pressure determines the amount of adsorption; extremely low temperature vacuum pipe due to gas transmission or leakage, the actual measured pressure rise there is a certain time delay, delay time and gas type, temperature and pipeline geometry are closely related.