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: 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: 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 cryocooler 8 is described which has a low magnetic signature in which a ceramic displacer 10 reciprocates within a helium impenetrable cold finger cylinder 12. A cyrogenic refrigerator formed by the displacer and the cold finger cylinder cools a cold space 22 to cryogenic temperature. The cold space 22 is magnetically shielded from a drive motor 18 which both drives the displacer 10 and compressor pistons 14, 15, 16. The motor is magnetically shielded by means of magnetic shields 70, 72, 74, 90, 76, 78, 80, 82.

Abstract: A face seal positioned between a first threaded member 12 and a second threaded member 10. The face seal provides effective sealing between rotatably secured members of a cryogenic refrigerator. The face seal comprises a seal space 32 formed by dual recess 18, 19 and 20, 21 on the first 12 and second 10 members. Disposed within the seal space is a triangular anti-rotation ring 24 and a packing member 22. The seal may be disposed upon a flange 48 in such a manner as to allow pressurized gas from a chamber 64 to pressurize the seal space 32. Further, the flange may be angled so as to apply a preset spring force upon the seal space. Alternatively, the anti-rotation ring may be a tubular member incorporating an angled flange to be positioned in a chamfer on one of the seal faces.

Abstract: A cryogenic refrigerator has a split seal at the interface between a displacer and cylinder. An expander ring presses the seal ring against the cylinder. The seal ring is also axially loaded against one face of a groove in which it is positioned. Preferred spring elements for axially loading the seal ring include a U-cross-section spring and a spring washer.