Cryosorption Vacuum Pumping under Fusion Reactor Conditions

摘要

Experiments are in progress on cryosorption pumping using a double-chevron pump with a molecular sieve pumping surface. Studies have been made with hydrogen, deuterium, helium, and deuterium-helium at 10 exp -7 to 3 x 10 exp -3 torr. Steady pumping speeds were observed for deuterium; above 10 exp -4 torr the speed increased with pressure until runaway occurred. At less than 10 exp -6 torr and low panel loading, hydrogen pumping speeds resemble those for deuterium. At higher pressures, the pump can function by condensation or sorption, and unsteady speeds are observed. Helium pumping is always by sorption, but regions of instability have been observed and defined. Deuterium-helium pumping tests showed that deuterium condensation on the panels prevents cryosorption of helium; however, compound pumps with separate panels for helium and hydrogen will be satisfactory. (ERA citation 03:002004)