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Vacuum pump is a kind of device which can get vacuum through mechanical, physical and chemical methods. The working principle of vacuum pump can be divided into two types: gas capture pump and gas transfer pump. The common vacuum extraction technology of vacuum pump can be divided into mechanical method and physical method.

1、 Mechanical law

1. Variable volume vacuum pump uses the periodic change of pump chamber volume to complete suction and exhaust to achieve the purpose of pumping. This kind of pump is divided into reciprocating and rotary type.

2. Momentum transfer pump, which relies on high-speed rotating blade or high-speed jet, transfers momentum to gas or gas molecules, so that gas continuously transfers from the inlet to the outlet of the pump. Molecular vacuum pump, steam jet pump and diffusion pump belong to this category.

2、 Physical method

The gas trapping vacuum pump is a kind of vacuum pump which makes the gas molecules adsorbed or condensed on the inner surface of the pump

1. Adsorption pump. It is a kind of trapping vacuum pump which can be pumped by the physical adsorption of adsorbent with large surface area (such as porous material).

2. Getter pump. It is a kind of vacuum pump which uses getter to capture gas chemically. Getters are usually metals or alloys in the form of blocky or deposited fresh films.

3. Getter ion pump. It is to make the ionized gas adsorbed on the surface of the getter material by the action of electric field or electromagnetic field, so as to achieve the purpose of pumping. It has the following two forms.

a. Evaporation ion pump: a vacuum pump in which the ionized gas is adsorbed on the suction material which is sublimated (or evaporated) intermittently or continuously in the inner wall of the pump, so as to realize the pumping.

b. Sputter ion pump: a vacuum pump in which ionized gas is adsorbed on the getter material continuously splashed from the cathode to realize the purpose of pumping.