Getter

A getter is a deposit of reactive material that is placed inside a <a href="/facts/Vacuum/BTk3goyV">vacuum</a> system to complete and maintain the vacuum. When gas molecules strike the getter material, they combine with it chemically or by <a href="/facts/Adsorption/ARH9peYM">adsorption</a>. Thus the getter removes small amounts of gas from the evacuated space. The getter is usually a coating applied to a surface within the evacuated chamber.
A vacuum is initially created by connecting a container to a <a href="/facts/Vacuum_pump/QTkV5dXr">vacuum pump</a>. After achieving a sufficient vacuum, the container can be sealed, or the vacuum pump can be left running. Getters are especially important in sealed systems, such as <a href="/facts/Vacuum_tube/VHd1BNLq">vacuum tubes</a>, including <a href="/facts/Cathode-ray_tube/8NVGx5C7">cathode-ray tubes</a> (CRTs), vacuum insulating glass (or vacuum glass) and <a href="/facts/Vacuum_insulated_panel/KYSA0Jtx">vacuum insulated panels</a>, which must maintain a vacuum for a long time. This is because the inner surfaces of the container release adsorbed gases for a long time after the vacuum is established. The getter continually removes residues of a reactive gas, such as oxygen, as long as it is desorbed from a surface, or continuously penetrating in the system (tiny leaks or diffusion through a permeable material). Even in systems which are continually evacuated by a vacuum pump, getters are also used to remove residual gas, often to achieve a higher vacuum than the pump could achieve alone. Although it is often present in minute amounts and has no moving parts, a getter behaves in itself as a vacuum pump. It is an ultimate chemical sink for reactive gases.
Getters cannot react with <a href="/facts/Inert_gas/3EkBEoYh">inert gases</a>, though some getters will adsorb them in a reversible way. Also, <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a> is usually handled by <a href="/facts/Adsorption/ARH9peYM">adsorption</a> rather than by reaction.

Getter open-in-new

Getter