How do the SU electric pumps work

4.1.1 Classification of vacuum pumps

In the case of vacuum pumps, a distinction is made between gas-conveying and gas-binding vacuum pumps. While the former can be used indefinitely, the latter have a limited gas absorption capacity and must be regenerated according to a specific, application-dependent rhythm.

Gas-conveying pumps, also called gas transfer pumps, are divided into positive displacement pumps and kinetic vacuum pumps. Positive displacement pumps convey gas from closed rooms into the atmosphere or into a downstream pumping stage. Kinetic pumps convey the gas by accelerating it in the pumping direction. This is done either by mechanical drive or by a directed jet of steam that is condensed at the end of the pumping section. Gas-binding vacuum pumps bind the gas either by physisorption at room temperature or lower temperatures or by chemisorption on clean surfaces. Chemisorption is technically realized by so-called getter pumps, in which pure getter surfaces are repeatedly generated by evaporation or sublimation or atomization (sputtering). If the gas particles to be bound are ionized in an ion getter pump before they interact with a getter surface, they can simultaneously clean the getter surface by sputtering and be buried by the atomized material. So-called non-evaporable getters (NEG) consist of very reactive alloys of mainly zirconium or titanium and have a very large specific surface. Gases can also penetrate the deeper layers of the getter material through micropores and are bound there as stable chemical compounds.

Figure 4.1: Overview of vacuum pumps