致冷机低温泵中光屏蔽问题的探讨

Study on Photoshielding of Refrigerator Cryopump

低温泵一级冷阵对外界热辐射的屏蔽效果将直接影响到泵的抽气速率、极限压强、抽气容量、致冷时间等抽气性能。本文作者从低温泵冷阵的整体结构进行全盘考虑，对致冷机低温泵一级冷阵的光屏蔽性能做了研究．作者用蒙特卡洛方法模拟光子在致冷机低温泵中的运动，从而计算出一级冷阵的光子透射率和二级冷阵对光子的吸收率，以此分析了冷阵表面不同部位上，不同的发射系数对屏蔽作用的影响，并根据不同的物理模型做了对比性计算，同时对部分计算结果进行了实验验证。得到了较为满意的结果。这项研究工作对低温泵冷阵结构的设计和冷阵表面处理工艺的选择具有一定参考价值。

The shielding function to the external radiation of heat for which the first cold shield of cryopump serves will have a direct effect on the specifications e.g pumping speed, ultimate pressure, pumping capacity, refrigerating time. On the basis of the monolithic construction of the cold shield of refrigerator cryopump was studied in this paper. The movement of photon in refrigerator cryopump was simulated with the Monte Carlo method. The transmitting rate of the first cold shield and the absorptivity of the second cold shield to photon were calculated. Therefore the influence of the various transmitting coefficients at different locations of cold shield on shielding function was analyzed and in accordance with the physical model, the comparative calculation was made. At the same time, the approval on part of calculating. results has been examined.This study has some references on the design of the construction of the cold shield and the selection of process of its surface.