Cryopump with selective condensation and defrost

Details Cryopump with selective condensation and defrost Cryopump with selective condensation and defrost

1997-11-25

1998-10-13

Capossela, Ronald C.

Refrigeration

Low pressure cold trap process and apparatus

62921, B01D 800

Patent

active

058195459

ABSTRACT:
The cryopanel of a cryopump can be preferentially defrosted to remove an acid-forming or toxic gas while leaving a second gas substantially condensed upon the cryopanel thereby limiting interaction between the vapor phases of the two gases. The cryopanel is warmed to a temperature within a selective defrost range at which the first gas selectively sublimates from the cryopanel. The temperature of the cryopanel is then maintained at a temperature within this range until the cryopanel is substantially cleared of the first gas leaving the second gas substantially undisturbed as a condensate upon the cryopanel. In a preferred embodiment, the cryopanel is maintained at about 50 to 85K during standard operation before being defrosted.

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