| 摘要 |
PURPOSE:To hold continuously the degree of vacuum in a vacuum container at a certain specific value, which is at or below the magnitude of order 10<-7> Torr, by such an arrangement that liquid helium is supplied to a liquid helium sump at any time from a depressurizing liquid helium sump. CONSTITUTION:If a liquid helium regulating valve 42 is opened little by little using a valve opening adjuster 44, the liquid helium 20 stored in a liquid helium sump 2 flows into a depressurizing liquid helium sump 41 through connecting pipes 45, 46 by the action of the pressure difference, and the temperature of the liquid helium 40 is held at a certain specific value, which is below 4.2 deg.K, to allow non-exhausted gas particles in vacuum containers 1, 14 to condense fast to the crio surface 41a so as to keep the degree of vacuum of the vacuum containers 1, 14 at a certain specific value below 10<-7> Torr. When the liquid helium 20 in the liquid helium sump 2 has decreased, liquid helium can be supplied at any time without changing the pressure in the depressurizing liquid helium sump 41, so that the degree of vacuum in the vacuum containers 1, 14 can be maintained at the specified value below 10<-7> Torr continuously. |
