Advanced Component Technology for Next Generation Cryocoolers

"Present day cryogenic refrigeration technology lacks a major component: a long-life, oil-free, dc-flow circulating compressor. Technology Applications, Inc. in collaboration with Scroll Labs, proposes to address this shortcoming by developing aninnovative oil-free scroll compressor with a potential operating lifetime in excess of ten years. The chief innovation is the "floating scroll" concept, which balances pressure and centrifugal forces acting on the scrolls, thereby minimizing forces oncontacting scroll surfaces to essentially eliminate wear. This concept is presently under development for medical applications involving oxygen concentration. We propose to drive this technology toward long-life cryocooler applications for both spaceflight and ground-based systems. Numerous shortcomings of both Stirling and pulse tube cryocoolers using flexure bearing linear compressors can be overcome if a long-life, dc-flow circulating compressor is developed: thermodynamic efficiencies at lowtemperatures, remote and distributed cooling, and vibration isolation. The primary goal will be to extend operational lifetime to ten years without maintenance intervals by improving mechanisms, materials, fabrication methods, and upgrading the designwith features not conducive to commercial cost constraints. Secondary goals include minimizing weight, input power, and induced vibrations such that this compressor can be used in the many applications w