Phenomenology of Bulk Gettering

The salient characteristics of bulk getters are reviewed. The operation of a bulk getter is explained by a theory which incorporates the effects of surface reactions and bulk diffusion. Solutions are summarized for the particular scenarios involving pumping at a constant pressure and desorption at a constant pumping speed. Hydrogen pumping and desorption measurements of ZrAl and ZrVFe bulk getters validate these predictions. From these data it is possible to extract the sticking coefficient, solubility and diffusivity. Using these materials parameters, the performance of the getter can be predicted for any operating regime. Related experiments which examine the isotopic dependence of the hydrogen solubility and a method for achieving the enhanced desorption of a hydrogen isotope are summarized.