| 摘要 |
PURPOSE:To restrict gas, invading into the vacuum under permeating through the wall of a vacuum vessel or being released out of the wall of the vessel, and obtain an extremely high vacuum space by a method wherein the space between the inside vacuum vessel and the outside vessel is filled with liquid nitrogen or liquid helium and the inside vacuum vessel is cooled. CONSTITUTION:The inside of the inside vacuum vessel 11 is evacuated by vacuum pumps 14, 15, 16, 17. When the degree of vacuum has arrived at 10<-4>-10<-6> Torr, the space between the inside vacuum vessel 11 and the outside vessel 12 is filled with liquid nitrogen or liquid helium 3 and the inside vacuum vessel 11 is cooled. The amount of gas, released out of the surface of a metal, is attenuated as time is elapsed at a normal temperature, however, the degree of vacuum will never become less than 10<-10> Torr within an actual operating time (0-10hr). The achieving degree of vacuum of the inside vacuum vessel is calculated as 10<-9> Torr, for example, in case the space between the inside vacuum vessel 11 and the outside vessel 12 is not filled with the liquid nitrogen or the liquid helium, however, the extremely high vacuum, less than 10<-11> Torr may be achieved when the inside vacuum vessel is cooled. |
