A gauge controller function that heats the grid of a hot cathode ionization gauge, by electron bombardment or by passing current through it, to drive off gas adsorbed on the electrodes. Without it, a gauge in UHV reads high because its own surfaces release gas under the electron beam. Degas is run below about 10⁻⁵ mbar after a bake or a vent, and the pressure rise during the cycle is normal.
Degas the B-A for ten minutes after the bake, then give it an hour before you write down base.
Also heard as
- degassing
- gauge degas
Related terms
Bayard-Alpert gauge
Hot cathode ionization gauge with a fine central collector wire, the standard gauge for high and ultra-high vacuum.
Ionization gauge
Gauge that reads high and ultra-high vacuum by ionizing gas molecules and measuring the resulting ion current.
Outgassing
Slow release of gas from the surfaces and bulk of materials inside a vacuum system.
Bake-out
Heating a vacuum system while pumping to drive off water and other adsorbed gas and lower the base pressure.