The theory and construction of a liquid helium cryogenic pump.
LaChance, George M.
Pucci, Paul F.
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Cryogenic pumping is a means of maintaining a high vacuum with large gas in-leakage rates. This is accomplished by the condensation and freezing of the gas molecules onto a surface that is maintained at a temperature well below the freezing point of the gas. A liquid helium filled "batch process" cryogenic pumping system was constructed and instrumented. The vacuum chamber and roughing system were obtained by the modification and redesign of an existing vacuum furnace. The theory of cryogenic pumping is presented and an approach developed for the evaluation of the cryopump performance.
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