Abstract: A vibration isolator particularly suited to isolating a closed cycle refrigerator in a cryopump includes a bellows having o-rings made of vibration damping material secured between the corragations of the bellows. A soft damping material maintains a low spring constant and also dampens all frequencies transmitted into the isolator.

Abstract: A pressure relief valve in a cryopump is preceded by a filter element in a filter housing. The filter element is springloaded so that the filter element itself provides pressure relief with clogging of the filter. The housing may have a removable end cap. The filter is spring biased by a spring between the housing end cap and a filter end cap.

Abstract: A vibration isolator particularly suited to isolating a closed cycle refrigerator in a cryopump includes two bellows covered with vibration damping material and separated by an intermediate mass. The damping material fills the spaces between corrugations of the bellows and is bonded to the bellows.

Abstract: In accordance with the invention, a hermetic refrigerant compressor pump which is used to compress helium is cooled by fins which are press fitted to the compressor's housing. The compressor is further cooled by a heat exchanger which cools oil in an oil sump located within the compressor housing. Preferably, a fan is located between the fins and the heat exchanger to help cool the pump.

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: This invention is comprised of an improved cryogenic refrigeration compressor which contains an externally adjustable relief valve positioned between the helium supply line and the helium return line whereby if the pressure within the helium supply line exceeds a predetermined value the externally adjustable relief valve opens up and allows helium to flow from the supply line to the return line. The relief valve is externally adjustable. It is comprised of a coaxial inlet and outlet member and externally adjustable spring compression means. Together they define a duct. Within the inlet member is a poppet valve and a spring. The spring exerts bias against the valve to close the valve against present fluid pressures.

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 recondenser with a primary heat exchanging surface for recondensing boil-off within a cryostat provides a second heat exchanging surface for removing heat leak into the cryostat. The second surface is cooled by the same working fluid that cools the primary surface, but at a temperature intermediate that of the primary surface and associated cooling apparatus which is remote from the cryostat. An intermediate transfer line transfers working fluid from an intermediate portion of the cooling apparatus to the second surface which is in heat exchange relation with a radiation shield of the cryostat but is out of physical contact with the radiation shield. The cooling apparatus includes a mechanical refrigerator which further cools working fluid returned from the second surface through the intermediate transfer line. The intermediate transfer line is preferably positioned in a non-contact helical manner about a final transfer line which carries the working fluid to the primary surface.

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 recondenser cycles a working volume of cryogen gas through a remote cold box and a coaxial recondensing, heat exchanger transfer line which is inserted into a cryostat. The working volume of gas is compressed to a high pressure and cooled through cooling means which include a mechanical refrigerator of the regenerator-displacer type. The cooled gas is expanded through a first JT valve to a medium pressure and further cooled. The further cooled medium pressure gas is transferred in a closed coaxial transfer line to a cryostat in which boil-off is recondensed. A second JT valve in the cryostat end of an inner tube coaxially positioned in an outer tube forming the transfer line expands the gas to a lower pressure and forms a liquid-gas mixture. The liquid-gas mixture is passed in heat exchange relation with the boil-off from an inner tube to an outer tube of a coaxial recondensing heat exchanger.

Abstract: The refrigerator of a cryopump is positioned within an insulating vacuum and the two stages of the refrigerator are selectively thermally coupled to first and second stage cryopanels. After initial rough pumping by an air ejector, rough pumping is completed during startup by coupling the cold first stage of the refrigerator to a first stage adsorption cryopanel. The second stage of the refrigerator is thereafter coupled to the second stage cryopanel. Thermal coupling of the refrigerator to the cryopanels is by means of spring biased thermal contacts brought into position by movement of the refrigerator. The thermal contact elements are provided with sufficiently large thermal masses to handle the large thermal loads of system startup.

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.

Abstract: The pressure relief valve is debris resistant, self-cleaning, and self-actuating in a cryopump. It includes an o-ring carried by a valve member within a valve cylinder. In opening, the valve member moves away from an end port to open vent ports in the side of the valve cylinder while withdrawing the o-ring to a debris free and protected region of the valve. As the valve member is moved into the closed position in response to an atmospherical pressure differential, a wiper ring cleans debris from the inner surface of the valve cylinder. A taper is provided on the inner surface of the cylinder to release compression on the vacuum sealing o-ring upon opening and to compress the o-ring as the valve member moves to the closed position. The wiper ring is expansible in order to provide a wiping action along the entire taper and prevent debris from reaching the o-ring. The end of the valve cylinder opposite to the end port serves as a shock absorber as the valve is opened.

Abstract: A cryopump is regenerated by means of an ejector pump which draws gas from the cryopump as the pump is warmed. The ejector is actuated by an inert gas. The same inert gas may also be used to purge the pump during evacuation.

Abstract: This invention is comprised of an improved cryogenic refrigeration compressor which contains an externally adjustable relief valve positioned between the helium supply line and the helium return line whereby if the pressure within the helium supply line exceeds a predetermined value the externally adjustable relief valve opens up and allows helium to flow from the supply line to the return line. The relief valve is externally adjustable. It is comprised of a coaxial inlet and outlet member and externally adjustable spring compression means. Together they define a duct. Within the inlet member is a poppet valve and a spring. The spring exerts bias against the valve to close the valve against present fluid pressures.

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: A pressure relief valve in a cryopump is preceded by a filter element in a filter housing. The filter element is springloaded so that the filter element itself provides pressure relief with clogging of the filter. The housing may have a removable end cap. The filter is spring biased by a spring between the housing end cap and a filter end cap.

Abstract: A cryogenic refrigerator includes opposing pistons driven by linear electromagnetic machines. Magnetic elements on armatures reciprocate adjacent to first and second flux paths and a transfer of flux between the flux paths with movement of either armature causes the other armature to move in a balanced fashion in an opposite direction. The armatures are driven by coils which transfer the flux from one flux path to the other. Tapers in the flux paths cause the armatures to seek a centered position, or are tailored to minimize compressor input power.

Abstract: In a cryogenic refrigeration system, a hermetic refrigerant compressor pump is used to compress helium. The compressor pump 10 is oil cooled by a heat exchange jacket 46 surrounding a compressor housing 28. Oil from an oil sump 30 within the compressor housing 28 is pumped through an external heat exchanger 44 where it is cooled, to the heat exchange jacket 46. From the heat exchange jacket 46, oil is recycled back to the oil sump 30. Pressure developed by the compressor pump 10 is used to pump the oil.