Helix Technology Corporation

John F Peterson

Allen J Bartlett

Philip A Lessard

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.

Temperature control of cryogenic systems

Orifices in a cooled plate throttle gases entering a cryopump. Selected orifices are closed by removable closures such as spring clips to allow the throttling to be varied.

Method and apparatus for throttling gas flow to a cryopump

A cryopump 20 for differentially pumping water vapor and inert gases from a work space comprising a two stage refrigerator 45 in which a radiation shield 32 substantially encloses a second stage cryopanel 40. The radiation shield 32 incorporates a baffle plate 34 which condenses higher condensing temperature gases and restricts passage of low condensing temperature gases through orifices 36 to the second stage cryopanel 40. Backside pumping ports 38 provide a flow path to the second stage refrigerator for residual gases within the cryopump 20. This creates a high vacuum within the cryopump and allows it to operate at maximum efficiency.

Reduced vacuum cryopump

A cryopump installation in which a novel cryopump 20 maintains a work chamber 12 at continuous high vacuum while periodically evacuating a load lock 14 in order to allow transfer of material from the load lock 14 to the work chamber 12 without disruption of the work chamber environment. The cryopump has pumping ports 46 positioned on the radiation shield 50 in order to pump plenum 72 to a high vacuum. Load lock gases enter the cryopump through port 46 and are condensed and adsorbed by the radiation shield 50 and second stage cryopanel 54.

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Lynnfield, MA, United States of America

John F Peterson