凹半球形轨道分子屏分子流场理论计算

Theoretical Calculation of Molecular Flow Fieldfor the Concave Hem ispherical W ake Shield Facility

借助一个封闭的球形理论模型， 对稳态非均匀分子流环境下的凹半球形轨道分子屏进行研究。计算了试验区分子数密度分布情况， 讨论了主要影响因素。结果显示： 利用凹半球形轨道分子屏可获得１０８分子数／ｍ ３ （等效于１０－ １２ Ｐａ） 的极高真空， 分子屏出气对试验区分子数密度的贡献是主要的， 分子屏粘附系数增大不能有效改善空载情况下分子屏试验区的真空度。

In this paper, the concave hem isphericalw ake shield facility ( C H W S F) isstudied w hich is in the state of steady, non uniform w ith the closed sphericaltheoreticalm odel. The distribution ofthe m olecularnum berdensity ofthe experim entalzone is calcu lated and the m ain effect factors are discussed. The result show s thatthe C H W S Fcan ob tain extrem e high vacuum levelw hose m olecular num ber density is about 108m - 3,the m aincontribution to the m olecular num ber density com es from the outgas ofthe C H W S F, andthe increasem ent of the coherent coefficient of the C H W S F can't effectively im prove thevacuum levelon occasion of absence ofgasload.