Low-Cost Cascade J-T Cryocooler with an Oil-Free Compressor

We propose to develop an inexpensive, high performance closed-cycle cascade J-T cryocooler. The cryocooler will be based on a high pressure ratio, oil-free, metal diaphragm compressor. This innovative compressor will be compact, inexpensive and extremely reliable. The compressor can either be used with single-stage mixed-gas or multi-stage cascade cycles. For a single-stage mixed gas cryocooler, the compressor will allow reduced cost and higher reliability due to the elimination of oil cleanup systems. It will also enable a new class of high performance low-cost cryocoolers based on the cascade J-T cycle. In Phase I we will design and fabricate a proof-of-concept model of this compressor, measure its volumetric efficiency and pressure ratio, and use it to drive a commercial mixed-gas J-T cold head. We will also show that the compressor will be inexpensive to manufacture in volume due to its lack of close-tolerance parts. In Phase II, we will design and fabricate a complete two-stage cascade J-T cryocooler. We expect that this cooler will exhibit a mean time to failure in excess of three years, be inexpensive to manufacture and offer efficiencies comparable to the best small Stirling cycle cryocoolers.