Generally, they are nothing more than mechanical, physical, chemical or physical and chemical methods.
Mechanical methods include:
1. Variable volume vacuum pump
It is a vacuum pump that uses periodic changes in the volume of the pump chamber to complete suction and exhaust to achieve the purpose of pumping. The gas is compressed before exiting the pump chamber. This type of pump is divided into two types: reciprocating type and rotary type.
Reciprocating vacuum pumps, rotary vane vacuum pumps, fixed vane vacuum pumps, slide valve vacuum pumps, trochoidal vacuum pumps, liquid ring vacuum pumps, dry vacuum pumps, and Roots vacuum pumps belong to this category.
2． Momentum transfer pump
It relies on high-speed rotating blades or high-speed jets to transfer momentum to gas or gas molecules, so that the gas can be continuously transferred from the inlet to the outlet of the pump.
Molecular vacuum pumps, water vapor jet pumps and diffusion pumps belong to this category.
Physical method:
Gas capture vacuum pump
It is a vacuum pump that causes gas molecules to be adsorbed or condensed on the inner surface of the pump. It can be divided into the following Several types.
1. Adsorption pump, which is a capture-type vacuum pump that relies on the physical adsorption of adsorbents with large surface areas (such as porous substances) to pump air. For example, molecular sieve adsorption pump.
2. Getter pump, which is a vacuum pump that uses a getter to chemically capture gas. Getters are usually metals or alloys in the form of bulk or deposited fresh films. For example, titanium sublimation pumps and zirconium-aluminum suction pumps belong to this type.
3. Getter ion pump, which makes the ionized gas adsorbed on the surface of the getter material through the action of electric field or electromagnetic field to achieve the purpose of pumping. It has the following two types.
1) Evaporation ion pump: The ionized gas in the pump is adsorbed on the suction material that sublimates (or evaporates) in an intermittent or continuous manner and covers the inner wall of the pump to achieve air extraction. . For example, orbital ion pump (or ballistic titanium pump).
2) Sputtering ion pump: A vacuum pump in which the ionized gas in the pump is adsorbed on the getter material continuously sputtered by the cathode to achieve the purpose of air extraction.
4. Cryogenic pump, which is a vacuum pump that uses low-temperature surfaces to capture gases.