Abstract: A retainer and spring with threaded end are machined from a single piece of material for threading to a piston in a closed cycle cryogenic cooler. Since the machined retainer and spring are a unitary part, they cannot rub against each other during operation of the piston which reduces debris generation. The spring is preferably formed as a double start helix which further increases axial stability and reduces side loading. The spring extends into an integrally formed, threaded end at the end thereof opposite the retainer.

Abstract: A unitary pulse tube expander for removable attachment to a SADA II coldfinger and insertion within a Dewar assembly. The regenerator of the pulse tube expander is encased in a regenerator sleeve and a cold cap to create a unitary pulse tube expander that may function as a drop-in replacement for a Stirling type expander in a SADA II coldfinger cryocooler.

Abstract: A unitary pulse tube expander for removable attachment to a SADA II coldfinger and insertion within a Dewar assembly. The regenerator of the pulse tube expander is encased in a regenerator sleeve and a cold cap to create a unitary pulse tube expander that may function as a drop-in replacement for a Stirling type expander in a SADA II coldfinger cryocooler.

Abstract: A retainer and spring with threaded end are machined from a single piece of material for threading to a piston in a closed cycle cryogenic cooler. Since the machined retainer and spring are a unitary part, they cannot rub against each other during operation of the piston which reduces debris generation. The spring is preferably formed as a double start helix which further increases axial stability and reduces side loading. The spring extends into an integrally formed, threaded end at the end thereof opposite the retainer. The spring is therefore solidly connected to its adjoining parts which greatly reduces tilting and off-axis movements inherent in the prior art, wound spring designs.

Abstract: This invention provides a low friction linear clearance seal for use in closed cycle cryogenic coolers. The clearance seal comprises a cylinder, a piston mounted within the cylinder for reciprocating movement and a self lubricating polymer liner bonded to the piston which forms an effective seal around the piston. The clearance seal improves the sealing capability between the piston and the cylinder and reduces heat generated by the motion of the piston along the cylinder wall. The clearance seal also improves the performance and reliability of the cryogenic cooler.