The solid state diffusion pump

The concept of a solid state diffusion pump is discussed. In such a device, ionized atoms are injected into a membrane which separates the pumped region and a higher pressure backing region. The injected ions are not stored indefinitely in this membrane as in ion pump geometry however but are transported across the membrane by diffusion. Diffusion across the membrane is enhanced by a thermal gradient or, more practically, by producing a defect gradient in the membrane by simultaneous ion irradiation from the backing region.