Cryopump

A cryopump, or cryogenic pump, is a vacuum pump that traps gases and vapors by condensing them onto a cold surface, and it is effective only on certain gases, since its effectiveness depends on the freezing and boiling points of a given gas relative to the cryopump's own temperature. Cryopumps are sometimes used to block particular contaminants, for example ahead of a diffusion pump to trap backstreaming oil or ahead of a McLeod gauge to keep out water; used this way they are called a cryotrap, waterpump or cold trap, even though the physical mechanism is the same as in a cryopump. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/