An ion-getter pump combines the operating principles of the getter pump and the ion pump. Molecules are ionized and attracted to an active-metal cathode, where they are buried and “sputter” active metal molecules onto the system walls. The active metal thus sputtered getters gas.
An excerpt:
“Ion getter pumps (also called sputter ion pumps or simply ion pumps) produce ultra-high vacuum (UHV) without the aid of moving parts or valves. This makes them highly effective, quiet, and low maintenance. Ion getter pumps require a large magnetic field within an isolated chamber and use high voltages to pull electrons into the assembly. Pumping relies on the sputtering of getter materials inside a series of cells and by the implantation or burial of the ions produced. The gas molecules pumped by chemisorption (gettered) and physisorption (ions) are now permanently “bound” and not able to “contribute” to the pressure inside the chamber. The process is quite extensive and complex, so in this blog, we will explain how ion getter pumps work and how they are used.”
Source: Vacuum Science World
