Investigation of getter-ion pump operation in systems containing oil and mercury vapour

Abstract

Details are given of some attempts to start a getter-ion pump which was heavily contaminated with oil vapour. Baking the pump while it was maintained under vacuum and the use of a liquid nitrogen cold trap are two methods of removing oil contamination and restoring pump operation. The effects of mercury vapour on an 8 litre/sec getter-ion pump are investigated. The getter-ion pump failed to operate with mercury vapour present at room temperature; however, in mercury vapour atmospheres less than 1 × 10 −5 torr the getter-ion pump worked satisfactorily. Continuous operation of the pump was possible with vapour pressures below 1 × 10 −7 torr without any apparent deterioration in pump performance.