| 摘要 |
PURPOSE:To flow a less amount of gas into a vacuum line and decrease load applied to a vacuum pump, by applying the separation between an electric discharge chamber and the vacuum line with a partitioning mechanism at the time of discharge starting when gas pressure is high in the discharge chamber. CONSTITUTION:Between an electric discharge chamber 2 and vacuum vessel 22, a selectively open-close controllable shutter 21 is provided, while the first vacuum pump 20 for evacuating the inside of the discharge chamber 2 is separately provided. At the time of starting when more quantity of gas must be introduced into the discharge chamber 2, the shutter 21 is closed to lower the pressure of gas in the discharge chamber 2 to about 10<-1>-10<-2> Pa and then opened after starting, thus quantity of gas flowing into the vacuum vessel 22 is decreased. Accordingly a load applied to a vacuum pump 23 can be decreased. |
