Shinku

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Working characteristics of the evapor type Ti getter pump have been studied as a function of the gas composition in the pump observed by a sector type mass spectrometer. In order to measure and control the rate of evaporation of Ti easily and accurately, the electron beam bombardment technique was used for evaporation of Ti.
The pumping speed and the ultimate pressure depend on the partial pressure of methane and inert gases in the pump.
Amount of methane in the pump decreased with flowing of N₂, CO₂ and other active gases. When Ti film was heated with above 40°C, the equilibrium partial pressure of methane increased gradually.
These observations about methane suggest that methane is formed on evaporated Ti film by the reaction between the impurity carbon in Ti metal and hydrogen produced by dissociation of H₂O or organic molecules. The detailed discussion of the processes, however, has not been carried out in the present paper.
The pumping speed of this pump is more than 10⁴ l/s for active gases. It is also proposed that the pumping system consists of this pump and the other type pumps for inert gases is useful for evacuation of the large volume high vacuum apparatus such as high temperature plasma testing devices or high energy particle accelerators.

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