Cold trap: Encyclopedia - Cold trap

Cold trap

Cold trap - Vacuum systems

In vacuum systems, a cold trap is a device used to trap particles by freezing them to the walls of a chamber. Sometimes it may be called a molecular sieve. It is also used with diffusion pumps to reduce oil backstreaming. See also cryopump.

Cold trap - Astronomy

In astronomy, a cold trap is a close to the surface layer of the atmosphere that is substantially colder than both the deeper and higher layers. It is called a trap because it keeps ascending gases with high melting points in by freezing them to a solid which then drops back to the planet surface. The most important gas to be kept in that way, on the Earth, is water vapor, which without the presence of a cold trap in the atmosphere (which for the earth resides at about 20 kilometers height) would gradually escape or dissociate into space, making life impossible.

Adapted from the Wikipedia article "Cold trap", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki