ABSTRACT
The pumping mechanism of capture pumps differs from the pumping principles employed in transfer pumps. Unlike in transfer pumps, gases are not transported via the pump and removed from the pump interior, but they are captured on the internal surfaces of pumps. In cryosorption pumps, particularly activated charcoals and zeolites have been used because of their very large surface areas as well as ability to adsorb real gases. The cryosorption pumps are substitution for roughing rotary pumps in applications where organic contamination or vibration is intolerable. Cryopumps with closed-loop helium circuits are well established and reliable constructions of cryopumps. Getter sublimation pumps belong to a group of capture pumps where pumping action is caused by capturing gases by chemisorption, chemical reaction, physical sorption, and solubility of the gas molecules in the sublimated metallic getters. Capture pumps cover the entire range of technical vacuum, including extreme high vacuum.
