Anti-Clogging, Flow-Regulating, Joule-Thomson CryostatGeneral Pneumatics Corporation (GPC), Phoenix, Arizona

InnovationGPC 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.

Accomplishments• 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

cryorefrigerators, 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.

Anti-clogging, Joule-Thomson Cryostat

Commercialization• 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.

Points of Contact: - NASA (Frank Howard, 407-867-4181) - GPC (Woody Ellison, 602-278-5678) SBIR Phase II; NAS10-11322

NASA Field Center: Kennedy Space CenterDate of Update: Sept. 15, 1998Success Story # 10-005

Government/Science Applications• 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 counterproliferation tactics has become increasingly crucial to global security.