パラレルルーバブラインド形クライオポンプの排気特性 : 多段の平行パネルを有するポンプの通過確率

抄録

As a new type of louvre blind cryopump, a parallel-louvre-blind cryopump with a rectangular chamber with opening distance B, louvre width C and depth D, is proposed. The influence of louvre size ratio R_c(=B/C) and pump depth size ratio R_d(=D/B) on the transmission probability P_bc is calculated by the Monte Carlo simulation and measured in model experiments. The following results are obtained. (1) The transmission probability of a cryopump designed with a dimensional ratio of R_d=1.28, is calculated as 0.7 at ratios of R_C=0.7∼0.9, which means that this type of cryopump can theoretically atttain a high pumping speed of more than 300 m³·s^-1/m² per opening area. (2) The transmission probability of the cryopump strongly depends on R_d and decreases rapidly for R_d less than 1.0 in the case of R_c=0.92.