SOLID STATE OXYGEN COMPRESSOR FOR JOULE-THOMMPSON CRYOCOOLERS

THE SIGNAL-TO-NOISE RATIO OF INFRARED DETECTORS INCREASES DRAMATICALLYAS THE TEMPERATURE OF THE DETECTOR IS REDUCED TO CRYOGENIC TEMPERATURES AND THERE HAS BEEN A SUBSTANTIAL IMPROVEMENT IN CRYOCOOLERS TO MEET THIS NEED. HOWEVER, VALVES OF ONE TYPE OF CRYOCOOLER, THE JOULE-THOMPSON EXPANSION CRYOCOOLER, ARE PRONE TO PLUGGING BY THE FREEZING OF IMPURITIES IN THE HIGH-PRESSURE STREAM. TO ADDRESS THIS PROBLEM, A RADICAL APPROACH FOR PROVIDING A HIGH-PRESSURE GAS STREAM OF 100% PURE OXYGEN TO A JOULE-THOMPSON EXPANSION DEVICE IS BEING INVESTIGATED. THE COMPRESSOR, A MONOLITHIC SOLID-STATE DEVICE CONTAINING NO MOVING PARTS, IS BASED ON THE SELECTIVE TRANSPORT OF OXYGEN IONS THROUGH A CERAMIC OXYGEN IONIC CONDUCTOR UNDER AN APPLIED VOLTAGE. ELEMENTARY CONSIDERATIONS SHOW THAT THE CERAMIC STRUCTURE MUST HAVE A VERY LOW RESISTANCE, THEREBY ELIMINATING THE PARTIALLY STABLIZED ZIRCONIAS. THE FEASIBILITY OF AN ALTERNATIVE, PROPRIETARY CERAMIC IS BEING ASSESSED THAT OFFERS TWO OUTSTANDING ADVANTAGES: OXYGEN IONIC CONDUCTIVITIES 30-50 LARGER THANTHE BEST ZIRCONIAS AND FAVORABLE SINTERING TEMPERATURES FOR FABRICATING VERY LOW RESISTANCE CELLULAR-HONEYCOMB STRUCTURES. BASEDON MEASURED OXYGEN-GENERATION RATES, MODEL CALCULATIONS ARE BEING CARRIED OUT FOR VARIOUS HONEYCOMB-TYPE GEOMETRIES TO STUDY POWER CONSUMPTION, PRESSURE, MASS-FLOW RATE, SIZE, AND EFFICIENCY. IDEAL JOULE-THOMPSON EXPANSION CYCLES ARE BEING STUDIED FOR REFRIGERATION CAPACITY AT TEMPERATURES 50-90K.