Non-evaporable getter, a sintered alloy such as zirconium-vanadium-iron or zirconium-aluminium, or a thin film coated inside a beam pipe. Heating it in vacuum, to about 200 °C for TiZrV beam-pipe films, 400 to 450 °C for ZrVFe and 700 °C or more for ZrAl, diffuses the surface oxide into the bulk and exposes a fresh, reactive surface. Once activated it pumps hydrogen very fast with no power, which makes it the standard partner of the ion pump in UHV and accelerator systems.
Activate the NEG at the end of the bake, otherwise it just loads up on all the water coming off the walls.
Also heard as
- non-evaporable getter
- NEG pump
Related terms
Getter
Reactive material that removes gas from a vacuum by binding it chemically to a fresh metal surface.
Ion pump
Capture pump that ionizes gas in a high-voltage magnetic discharge and buries the ions in titanium.
Bake-out
Heating a vacuum system while pumping to drive off water and other adsorbed gas and lower the base pressure.
UHV
Ultra-high vacuum: pressures below about 10⁻⁷ mbar, reached only with baked, metal-sealed systems.