Patent ID: 6550256
Filing Date: 2003-04-22
Classification: F04D,Y10S

Abstract:
A method for obtaining a very low partial pressure of hydrogen in an ultra-high or extreme high vacuum condition in a vacuum system comprising:A) a vacuum chamber connected to a vacuum pumping system comprising: i) a turbomolecular pump connected to; ii) a roughing pump connected to said turbomolecular pump via a first conduit that includes a first cut off valve; and iii) a cryopump connected to said turbomolecular pump via a second conduit that includes a second cut off valve and further including a coating of palladium oxide on at least a significant portion of the interior surface of said cryopump â€ƒsaid method comprising: a) cleaning said vacuum chamber and related components with ultra pure water; b) baking out at a temperature above about 425Â° K.; c) evacuating said cryopump and said vacuum chamber to a pressure below about 1.eâˆ’3 Torr with said roughing pump while said first cut off valve is open; d) closing said first cut off valve; e) opening said second cut off valve; f) activating said cryopump to obtain a temperature below about 150Â° K. in said vacuum chamber and said cryopump; and g) completing evacuation of said vacuum chamber with said turbomolecular pump.