Abstract: A cryopump with quicker adsorption of non-condensible gases is disclosed. The second stage cryopanel of this cryopump is comprised of an array of discs spaced along an axis perpendicular to the frontal cryopanel, and in close thermal contact with the second stage heat sink. Each disc of the array is bent toward the frontal cryopanel at the outer edge of the disc and is flat radially inward from the bend. Each disc is coated with adsorbent material on the surface away from the frontal cryopanel radially inward from the bend in the disc.

Abstract: In an expansion engine used in cryogenic refrigeration, a stepped inlet valve 10 and a stepped exhaust valve 11 are fluid activated to control high pressure gas such as helium into and out of the engine. Clearance seals in the stepped valve are achieved by sizing a small diameter of a stepped piston to a small bore and by sizing a sleeve 16 to a larger diameter of the stepped piston. The sleeve 16 fits loosely within a large bore, and is fixed into position by placing a wire of soft metal 9 between the sleeve and the wall of the cylinder.

Abstract: To control the temperature of one or more heat sinks of a cryogenic refrigerator in a cryopump, refrigerant gas to the refrigerator is diverted through heat exchangers associated with the refrigerator heat sinks. The diverted refrigerant gas may be used to maintain the temperature of the first stage cryopumping surfaces above some level to avoid cross over hangup. The second stage cryopumping surfaces may be warmed by the diverted refrigerant to some temperature level for partial regeneration. Both heat sinks may be warmed for full regeneration of the cryopump. Bleed flow of refrigerant gas cooled by the first stage of the refrigerator can be directed past a thermal mass to cool that mass. By reversing the flow of refrigerant gas during cooldown of the system, the thermal mass can be used to more rapidly cool the refrigerator. The thermal mass is thermally isolated from the refrigerator heat sinks and is positioned within the vacuum vessel of the cryopump adjacent to the first stage of the refrigerator.

Abstract: A cryopump 20 with increased adsorptive capacity comprising a honeycomb adsorption structure 46 positioned within a second stage chevron assembly 40. Multiple chambers 58 of the honeycomb are covered with adsorbent charcoal 68. The entire structure 46 is attached to a second stage 52 of a cryogenic refrigerator 45.

Abstract: Valves for controlling process gas at the cold end of an expansion engine are fluid actuated. The actuating fluid is controlled by a solenoid actuated spool valve positioned at ambient temperature. The fluid is cooled in a thermally regenerative flow path extending between the solenoid actuated valve and the fluid actuated valve.

Abstract: The invention discloses a cryopump comprising a primary cryopanel 67 associated with a low temperature heat sink 60 having means for adsorbing a first low boiling point gas and a secondary cryopanel 80 associated with heat sink 60 and a higher temperature heat sink 48 having means for condensing a higher boiling point gas. There are means 90 for selectively conducting heat to the primary cryopanel to raise the temperature of the cryopanel above that which is necessary to cause said first gas to become desorbed from said cryopanel while having minimal effect on the capacity of the higher temperature heat sink.