Anti-Clogging, Flow-Regulating, Joule-Thomson Cryostat

General Pneumatics Corporation (GPC)

Phoenix, AZ

GPC developed a patented new type of Joule-Thomson (J-T) cryostat featuring exclusive anti-clogging, flow regulation capabilities to satisfy a need to provide very low temperature cooling for infrared sensors, super conductors, supercooled electronics, spacecraft, nuclear contamination detectors, and cryosurgery.

• As a result of a NASA SBIR contract, GPC developed a J-T cryostat that can operate continuously with gas contamination levels that would quickly clog conventional cryostats. GPC cryostats employ a more rugged and stable means of flow regulation than the conventional ones, and can be equipped with a manual or actuator driven flow adjustment which is especially useful in developmental and laboratory applications. The patented anti-clogging, flow-regulating features have been incorporated in cryostats ranging in cooling capacity from ¼ watt to 50 watts
• GPC has manufactured J-T Cryostats in small production runs for custom design applications
• GPC’s Western Research Center (GP WRC) was specifically established to research and develop cryorefrige- rators, Stirling engines and refrigerators, and new approaches for thermal management and energy conversion
• GPC, founded in 1959, has established world-wide recognition for the custom design and manufacture of high reliability pneumatic and hydraulic valves, pressure regulators, aspirators, and accumulators for aerospace applications

• GPC has designed and produced custom J-T cryostats for NASA-JPL, Sandia-LNL, BEI Systron Donner, Aerojet ESD, EG&G, Bechtel Nevada, and CryoGen. Prospective applications have included spacecraft, computer electronics, nuclear contamination detection and counter-proliferation, and cryosurgery
• One development was a highly sophisticated, adjustable, two-stage xenon/krypton cryostat assembly for Aerojet ESD. GPC also designed an anti-clogging cryostat to continuously produce solid hydrogen at 10 K
• Another cryostat was successfully tested at NASA-JPL in an experimental 80 K sensor cooler, which achieved a temperature stability 3 orders of magnitude better than conventional cryostats.

A recent development for the U.S. Dept. of Energy Remote Sensing Laboratory, operated by Bechtel Nevada, is a common module-size (0.204-inch bore, 2.62-inch deep coldwell) self-regulating cryostat which produces up to 16 watts of refrigeration for several hours using 3000 psi argon to cool a HPGe gamma ray detector to below 100 K
• For CryoGen, GPC provided a prototype anti-clogging cryostat for a closed-cycle cryosurgery system.

Cumulative sales revenues to date by target market sector are approximately $1 million
The remaining technological or business development necessary for large volume commercialization and joint ventures depends on securement of the patent currently in process to allow marketing promotion
• There have been two patents granted, and another one is in process

• The specific objective of the NASA KSC Phase I SBIR project was for GPC to design, build, and test a prototype self-regulating Joule-Thomson cryostat incorporating an anti-clogging nozzle with flow regulation by differential thermal expansion coefficients and a manual adjustment means. GPC’s cryostat, initially sized to meet ¼ watt common module requirements, demonstrated continuous operation in simultaneous testing using commercial grade nitrogen with contamination levels which repeatedly clogged conventional cryostats within 6 minutes
• In Phase II, the cryostat design was extended to 50 watts cooling capacity at 77 K. The cryostat was incorporated into a prototype closed-loop cryocooler featuring a new oil-free sealed high- pressure compressor and novel closed-loop control scheme, which was delivered to KSC in September 1988
• Later, GP WRC worked with EG&G ORTEC in Oak Ridge, Tennessee to apply the technology to cooling high-resolution gamma-ray spectrometers, under a contract to Bechtel Nevada. The U.S. Department of Energy’s Remote Sensing Laboratory in Nevada directed the development
• The cryostat development is a key part in the development of more portable high-purity germanium gamma-ray detectors. These are necessary to discern among radionuclides in medical, fuel, weapon, and waste materials. The ability to monitor nuclear materials, verify possible hazards, and develop counterproli- feration tactics has become increasingly crucial to global security

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