Abstract: A miniature cryogenic cooling system having low microphonics and thermophonics. The apparatus includes a cold finger incorporating primary and secondary working volumes and their associated regenerative beds. Both volumes are adapted to effect cooling. A displacer reciprocates within the cold finger under the influence of push-pull pressure waves from a dual compressor assembly. The cold finger includes an arrangement for providing pneumatic cushioning of the reciprocating displacer to control displacer slamming.

Abstract: A capacitive pressure or vacuum gauge is disclosed that utilizes a transducer in which a change in capacitance between a movable conductive diaphragm and the wall of the transducer is used to sense changes in pressure or vacuum. The change in capacity is converted directly into a change in frequency of a digital signal by means of a simple resistance/capacitance oscillator in which the capacitive transducer is used as the capacitance.

Abstract: A miniature cryogenic system preferably operating in a manner similar to a split Stirling cycle utilizes a cold finger with a solid, low weight displacer and a stationary regenerative material external to the displacer. The regenerative material preferably surrounds the displacer and extends from a fluid inlet to a cooled end plate of a housing. The displacer has a central channel that receives an auxiliary displacer that carries a regenerative material in an internal cavity. A second fluid inlet located at the end of the housing opposite the cooled end communicates with the regenerative material held in the auxiliary displacer. The main and auxiliary displacers preferably have associated heat exchangers at their cooling ends and the cooling end of the auxiliary displacer is located to pre-cool the fluid passing from the first inlet to the cooled end plate.

Abstract: A miniature cryogenic cooling system having low microphonics and thermophonics. The apparatus includes a cold finger incorporating primary and secondary working volumes and their associated regenerative beds. Both volumes are adapted to effect cooling. A displacer reciprocates within the cold finger under the influence of push-pull pressure waves from a 180.degree. opposed compressor assembly. The cold finger includes an arrangement for providing pneumatic cushioning of the reciprocating displacer to control displacer slamming.

Abstract: An improved valve is provided for controlling the flow of working fluid in a cryogenic refrigerator of the type comprising a reciprocating displacer. The valve has a slidable valve member which is arranged to alternately introduce working fluid to or remove working fluid from a cooling chamber in response to reciprocating movement of the displacer. The valve is constructed so as to make certain that sliding movement of the valve member is not restricted by the working fluid.