cryopumppi

A cryopump is a type of vacuum pump that operates at very low temperatures. It uses a cold surface, typically cooled to cryogenic temperatures, to condense or adsorb gas molecules from the vacuum chamber. As gas molecules come into contact with the cold surface, they lose kinetic energy and become trapped, thereby reducing the pressure in the chamber.

The primary mechanism of cryopumping involves two main processes: condensation and adsorption. Condensation occurs when gas molecules at a sufficiently low temperature and pressure transition directly from the gaseous to the solid phase (deposition). Adsorption involves gas molecules adhering to the surface of a cryosorbent material, such as activated charcoal or zeolites, which are also cooled to cryogenic temperatures.

Cryopumps are highly effective at pumping a wide range of gases, especially water vapor, which is often the dominant residual gas in vacuum systems. They are particularly useful for achieving ultra-high vacuum (UHV) levels due to their ability to pump light gases and their inherent cleanliness, as they do not introduce oil or other contaminants into the vacuum system.

Applications of cryopumps include semiconductor manufacturing, space simulation chambers, particle accelerators, and scientific research requiring ultra-high vacuum environments. The performance of a cryopump is influenced by factors such as the pumping speed, base pressure achievable, and the capacity for gas accumulation. Regular regeneration, which involves warming the pump to release the trapped gases, is necessary to restore its pumping capacity.