Abstract: Apparatus for vacuum pumping an enclosed chamber without the use of activated charcoal to remove hydrogen by cryosorption. As a result, the potential for contamination by a sorbent material is eliminated. The pumping structure includes an integral two-stage vacuum pump. The first-stage pump is a cryogenic pump having a pump chamber and cryoarrays mounted on an expander for cryocondensation of the principal gases present in the vacuum chamber. The second-stage pump operates at room temperatures and includes one or more getter pumps whose principal function is to remove hydrogen molecules that may be present in the vacuum chamber after the first-stage cryopump has removed most of the cryocondensable gases from the vacuum chamber. In one aspect of the invention, the first-stage pump is separated from the second-stage pump by a gate valve to protect the getter pumps during the regeneration flushing of nitrogen through the first-stage cryogenic pump chamber.

Abstract: Cryopump apparatus and method for controlling the operating temperature of a cryoarray in a cryopump. The cryopump has means for thermally isolating one of more of the cryoarrays from the refrigeration source. The means for thermally isolating is a thermal switch formed from at least first and second switch elements made of materials having dissimilar coefficients of thermal expansion. The thermal switch is also used in isolating one of the pump's cryoarrays during a partial regeneration process. The thermal switch of the preferred embodiment may also be used to prevent one of the pump's cryoarrays from falling below a predetermined operating temperature.

Abstract: A linear drive motor of a cryogenic refrigerator, where a reciprocating armature (10) which alternately compresses and expands a gaseous fluid in a thermodynamic cycle, is supported at both ends by flexure supports (110, 130). The armature has a clearance seal (150) with a stationary piston (11) attached at one end to the armature housing by a flexible stem (11B) to minimize cross-bearing loads between the armature and the stationary piston along the clearance seal.

Abstract: In a cryogenic refrigeration utilizing a linear drive motor, a temperature control system controls the displacement of an armature reciprocating at a fixed frequency to adjust the operating temperature of a working fluid at the cold end of a cold finger. Linear drive motors using dynamic absorbers to reduce vibration operate within the narrow frequency range to which the absorber is tuned. Controlling the maximum displacement of the armature used to compress the working fluid results in the ability to adjust the temperature at the cold end of the refrigeration without altering the frequency of operation.

Abstract: A linear motor compressor within a cryogenic refrigerator wherein the compressor space, within which a gaseous fluid is alternately compressed and expanded, is formed by a stationary piston and a reciprocating armature that is concentric about the piston. The armature is supported along a clearance seal the stationary piston. An axial bore along the stationary piston conveys gaseous fluid from the compression space to a displacer within the cold finger of the cryogenic refrigerator. An isolator for reducing transimission into and out of the compressor comprising a dynamic absorber and flat springs mounted with a damping material between the compressor and a mounting frame. A sensor for detecting the position of the armature utilizes a target magnet whose magnetic flux lines are decoupled from the flux lines generated about the coil.

Abstract: A two mass vibration isolator particularly suited to a linear reciprocating machine. Vibration into and out of the machine is attenuated by an isolator placed between the machine and its mounting frame. The isolator is an elastomer with a damping ratio of at least 0.1 sandwiched between two retainers.

Abstract: A linear drive motor of cryogenic refrigerator in which a reciprocating armature alternately compresses and expands a gaseous fluid in a thermodynamic cycle. An isolator system comprising a countermass, having an antiphase movement with respect to the armature is centrally mounted on unitary springs. Isolator springs are mounted between the compressor and the compressor housing such that vibrations in to and out of the system are attenuated.

Abstract: A linear drive motor of a cryogenic refrigerator, where a reciprocating armature which alternately compresses and expands a gaseous fluid in a thermodynamic cycle, is supported at both ends by flexure supports. The armature has a clearance seal with a stationary piston attached at one end to the armature housing by a flexible stem to minimize cross-bearing loads between the armature and the stationary piston along the clearance seal.

Abstract: A two mass vibration isolator particularly suited to a linear reciprocating machine. Vibration into and out of the machine is attenuated by an isolator placed between the machine and its mounting frame. The isolator is an elastomer with a damping ratio of at least 0.1 sandwiched between two retainers.

Abstract: In a cryogenic split Stirling refrigerator, the compressor is driven by linear drive motors. Each linear drive motor has an armature hermetically sealed by a housing 20. Surrounding the housing is a stator formed from two bodies each housing a drive coil 48 and 49. Each body consists of two components 52-55 formed from involute laminations which have been aligned after the coil has been inserted. Separating the bodies is a magnet 56.