On Predicting Transient Pressure in Vacuum Systems Featuring Getter Materials

Getter materials have been used to reduce pressure or partial pressures in a variety of vacuum applications ranging from vacuum tubes to space flight science instruments. Testing of getter materials has tended to emphasize the capacity of candidate materials to collect specific gas species in sufficient quantities to size them in these applications. When determining a getter material’s capacity, it is typically subjected to enough excess target gas to ensure it sorbs as quickly as possible. However, when both the gas source strength and the getter’s sorption rate exhibit transient decay behavior, such data is not sufficient to predict the targeted species’ partial pressure within a vacuum system as a function of time.