:Getter Pumps:
Getter pumps depend upon the reactionof gases with reactive metals as a pumping mechanism;such metals were widely used in electronic vacuum tubes, being described as getters (Reimann, 1952). Production
techniques for the tubes did not allow proper outgassing of tube components, and the getter completed the initial pumping on the new tube. It also provided continuous pumping for the life of the device.
Some practical getters used a ‘‘flash getter,’’ a stable compound of barium and aluminum that could be heated, using an RF coil, once the tube had been sealed, to evaporate a mirror-like barium deposit on the tube wall. This provided a gettering surface that operated close to ambient temperature. Such films initially offer rapid pumping, but once the surface is covered, a much slower rate of pumping is sustained by diffusion into the bulk of the film. These getters are the forerunners of the modern sublimation pump.
A second type of getter used a reactive metal, such as titanium or zirconium wire, operated at elevated temperature;gases react at the metal surface to produce stable,low-vapor-pressure compounds that then diffuse into the interior, allowing a sustained reaction at the surface.These getters are the forerunners or the modern nonevaporable getter (NEG).
Getter pumps depend upon the reactionof gases with reactive metals as a pumping mechanism;such metals were widely used in electronic vacuum tubes, being described as getters (Reimann, 1952). Production
techniques for the tubes did not allow proper outgassing of tube components, and the getter completed the initial pumping on the new tube. It also provided continuous pumping for the life of the device.
Some practical getters used a ‘‘flash getter,’’ a stable compound of barium and aluminum that could be heated, using an RF coil, once the tube had been sealed, to evaporate a mirror-like barium deposit on the tube wall. This provided a gettering surface that operated close to ambient temperature. Such films initially offer rapid pumping, but once the surface is covered, a much slower rate of pumping is sustained by diffusion into the bulk of the film. These getters are the forerunners of the modern sublimation pump.
A second type of getter used a reactive metal, such as titanium or zirconium wire, operated at elevated temperature;gases react at the metal surface to produce stable,low-vapor-pressure compounds that then diffuse into the interior, allowing a sustained reaction at the surface.These getters are the forerunners or the modern nonevaporable getter (NEG).
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