What is cryopumping?

Cryopumping is a process of vacuum pumping in which gases and vapors are removed from a sealed chamber by using extremely low temperatures. This process is used in many industries including semiconductor, aerospace, and pharmaceuticals.

In cryopumping, a cryogenic cooling agent (such as liquid nitrogen) is used to cool a surface, typically made of copper, to extremely low temperatures, usually below -150°C. The gas molecules inside the chamber come in contact with this cryogenically cooled surface and freeze onto it, trapping them and removing them from the chamber.

Cryopumps are known for their high pumping speeds, and ability to pump a wide range of gases including hydrogen, helium, and nitrogen. They are used when clean high vacuum conditions are required and are preferred over other types of vacuum pumps because they don't introduce any contaminants into the chamber.

While cryopumping has many benefits, including high pumping speeds and low contamination, it also has some limitations. The process requires cryogenic cooling to achieve ultra-low temperatures, therefore, the operation is typically more complex and expensive than other vacuum pumping techniques. Cryopumping is also limited in its ability to pump high-molecular-weight molecules, including some hydrocarbons and lubricants.