By its principle cryopumps belong to sorption pumps, this means that gas doesn't pass through the pump but it's bound directly to a specific element of the pump. Principles of cryocondensation, cryoadssorption or cryotraping are being used. Due to the fact that cryopump doesn't need any medium for its function (cooling liquid is outside of the vacuum part of the pump) the main benefit of this pump is the reduction of the risk of contamination of the pumped space. Extremely low pressures (below 10-10 hPa) and very fast speed of pumping can be achieved. The pumping speed of the cryopump is given by the number of molecules falling per unit area per time unit and is in order of tens of liters per cm2 - according to the type of pumped gas.
Cryopumps are not suitable for pumping from atmospheric pressure and it's difficult to pump gases such as hydrogen, helium or neon.
Cryogenic pumps are mainly used in thin film coating technology, sputtering devices, particle accelerators, etc.