Mass spectrometric studies of a vacuum system fitted with both getter-ion and sublimation pumps

Abstract

The operation of a titanium sublimation pump with various types of filament is described. The partial pressures of residual gases in a stainless steel system were investigated during pump-down and also at the base pressures reached. The main residual gas after getter-ion pumping was hydrogen. The use of a sublimation pump in parallel with the getter-ion pump reduced the pressures of all gases, the main reduction being with hydrogen. A sublimation pump used alone did not pump the inert gases, but rapid pumping of all gases present was observed when both pumps were used together. The composition of residual gases after the pressure had fallen to 10 −5 torr during a normal pump-down was not greatly affected by the gas used for filling. At this pressure the composition was determined mainly by the gases evolved from the walls of the system.