A cryopump is a vacuum pump that uses a low temperature surface to condense gas, also known as a condensate pump. The cryopump can obtain a clean vacuum with the highest pumping rate and the lowest ultimate pressure, and is widely used in the research and production of semiconductors and integrated circuits, as well as molecular beam research, vacuum coating equipment, vacuum surface analysis instruments, ion implanters and space simulation. devices, etc.
Pumping principle The cryopump is equipped with a cold plate cooled to a very low temperature by liquid helium or a refrigerator. It condenses the gas and keeps the vapor pressure of the condensate below the ultimate pressure of the pump, so as to achieve the pumping effect. The main functions of low temperature pumping are low temperature condensation, low temperature adsorption and low temperature capture.
cryopump
① Low temperature condensation: gas molecules condense on the surface of the cold plate or on the condensed gas layer, and the equilibrium pressure is basically equal to the vapor pressure of the condensate. When pumping hydrogen, the cold plate temperature is lower.
②Low temperature adsorption: The gas molecules are adsorbed on the surface of the adsorbent coated on the cold plate with a thickness of one molecular layer. The equilibrium pressure for adsorption is much lower than the vapor pressure at the same temperature.
③Cryogenic trapping: Gas molecules that cannot be condensed at the extraction temperature are buried and adsorbed by the growing layer of condensable gas.