A method of operating an evaporation pump system in a chamber at partial vacuum is provided. The method includes heating a getter source to form a getter vapour; depositing the getter vapour onto a first target surface arranged within the chamber to form a getter layer; and providing a replenished target surface within the chamber, and onto which the getter vapour can be deposited, by at least partially removing, from the first target surface, the getter layer and any chemisorbed, and/or physisorbed products present within the getter layer, said step being carried out within the chamber; and/or arranging a second target surface within the chamber, wherein, the getter source comprises lithium.