This SmallBusiness Innovation Research Proposal is concerned with research and development of an low cost, compact, light weight, energy-efficient long-life, low maintenance, low mechanical vibration, low electromagnetic induction closed cycle refrigeration capable of providing 100 milliwatts of cooling at 10 K as well as cryogenic cooling at higher temperature. The refrigerator is intended for use with cryogenic sensors, and cold electronic devices, superconducting and semiconducting instruments, Josephson voltage standards and IR imaging cameras for both space-borne and terrestrial applications. The type of refrigerator proposed for development is an innovative novel variant of the two-stage pulse tube refrigerator with warm end expander. The pressure wave generators used for both stages are hydraulically driven diaphragm compressors. Diaphragm expanders are used for both warm end expanders. The expanders operate synchronously with the compressors but lead in phase by approximately one-quarte cycle. The pulse tubes are coaxial with and are enclosed within the regenerator matrices. The regenerator matrices comprise sintered metal powder elements of annular form. Rare earth metal powders are used for the regenerator elements at the lowest temperatures int he second stage. The two stages of the pulse tube generate refrigeration at two temperature levels in the range of 5 - 20 K in one case and 50 - 90 K in the other. The two stages may be deployed in an extended tandem geometry but the alternative folded parallel geometry is generally more convenient. Anticipated Benefits and
Potential Commercial Applications: Versions of the proposed pulse tube cryocooler would be highly advantageous for a variety of applications requiring prolonged continuous low-noise cryocooling and/or commandable control of a robust, low cost cryocooler able to operate lfor long periods without maintenance. It is suitable for diverse commercial application including infrared spectrometers and imagers, x-ray spectrometers, cryosurgery instruments, computers, communications, and electronic systems. It can be provided in a range of sizes and capacities and is capable of operating over a wide tempeature range.
