Combination of a cryopump and a non-evaporable getter pump in applications

A preliminary study on the pumping performance of a cryopump combined with a high-capacity non-evaporable getter (NEG) pump was performed. The pumping speed, the pump-down time, and the gas composition in a standard UHV chamber were evaluated using the cryopump alone and combined with a high capacity getter pump made from sintered porous getter material. In order to exploit the high specificity of the getter pump for hydrogen and water vapor, the cited quantities were measured both before and after a baking treatment. It was found that the ultimate pressure in the baked chamber could be greatly improved using the getter pump and that pump-down times of the unbaked chamber were consistently reduced due to the very high pumping speed of NEGs for water vapor.