Vacuum Pumps

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A rotary vane vacuum pump is a positive-displacement pump that consists of vanes mounted to a rotor that rotates inside a cavity. In some cases these vanes can have variable length and/or be tensioned to maintain contact with the walls as the pump rotates

 A turbomolecular pump is a type of vacuum pump, superficially similar to a turbopump, used to obtain and maintain high vacuum. These pumps work on the principle that gas molecules can be given momentum in a desired direction by repeated collision with a moving solid surface.  Turbo vacuum pumps are now the most popular choice in high vacuum systems.

A cryopump or a "cryogenic pump" is a vacuum pump that traps gases and vapours by condensing them on a cold surface, but are only effective on some gases. The effectiveness depends on the freezing and boiling points of the gas relative to the cryopump's temperature. 

 A scroll compressor (also called spiral compressor, scroll pump and scroll vacuum pump) is a device for compressing air or refrigerant. It is used in air conditioning equipment, as an automobile supercharger (where it is known as a scroll-type supercharger) and as a vacuum pump. Many residential central heat pump and air conditioning systems and a few automotive air conditioning systems employ a scroll compressor instead of the more traditional rotary, reciprocating, and wobble-plate compressors. 

An ion pump (also referred to as a sputter ion pump) is a type of vacuum pump which operates by sputtering a metal getter. Under ideal conditions, ion pumps are capable of reaching pressures as low as 10−11 mbar 

 A titanium sublimation pump (TSP) is a type of vacuum pump used to remove residual gas in ultra high vacuum systems, maintaining the vacuum 

 The definition of a dry vacuum pump is a pump that does not use any fluids to create a vacuum or contact the process gas and can also discharge to atmosphere. ... Timing gears with oil reservoirs and close clearances between the rotors and housing are additional attributes that make up a dry vacuum pump 

Diffusion pumps use a high speed jet of vapor to direct gas molecules in the pump throat down into the bottom of the pump and out the exhaust. They were the first type of high vacuum pumps operating in the regime of free molecular flow, where the movement of the gas molecules can be better understood as diffusion than by conventional fluid dynamics. Invented in 1915 by Wolfgang Gaede, he named it a diffusion pump since his design was based on the finding that gas cannot diffuse against the vapor stream, but will be carried with it to the exhaust. However, the principle of operation might be more precisely described as gas-jet pump, since diffusion plays a role also in other high vacuum pumps. In modern textbooks, the diffusion pump is categorized as a momentum transfer pump. 

A molecular drag pump is a type of vacuum pump that utilizes the drag of air molecules against a rotating surface. The most common sub-type is the Holweck pump, which contains a rotating cylinder with spiral grooves which direct the gas from the high vacuum side of the pump to the low vacuum side of the pump. The older Gaede pump design is similar, but is much less common due to disadvantages in pumping speed.In general, molecular drag pumps are more efficient for heavy gasses, so the lighter gasses (hydrogen, deuterium, helium) will make up the majority of the residual gasses left after running a molecular drag pump.

The turbomolecular pump invented in the 1950s, is a more advanced version based on similar operation, and a Holweck pump is often used as the backing pump for it. The Holweck pump can produce a vacuum as low as 1×10−8 mmHg (1.3×10−6 Pa)