Development of a 1W, 10 K Reverse Brayton Cycle Crycooler

50069-98-I Development of a 1W, 10 K Reverse Brayton Cycle Crycooler--Doty Scientific, Inc., 700 Clemson Road, Columbia, SC 29229-4339; (803) 788-6497 Dr. F. David Doty, Principal Investigator Mr. George Entzminger, Business Official DOE Grant No. DE-FG02-98ER82565 Amount: $75,000 High sensitivity detectors (of infrared and x-ray radiation and magnetic fields) require miniature, fieldable cryocoolers with low cooling capacity (one watt) continuous cryogenic cooling (to 10 K or lower). However, the severe vibration of available cryocoolers seriously degrades sensitivity and image quality. Although too large for this application, Reverse Brayton Cycle (RBC) cryocoolers with turbo-expanders and turbo-compressors are known to have negligible vibration and other advantages. Therefore, this project will develop a micro-expander based on similar principles. Ceramic microturbines (rotor diameter ~4 mm) will be developed which have been proven in Nuclear Magnetic Resonance (NMR) sample spinners at over 1.3 million rpm. Phase I will design a novel RBC cryocooler and complete a series of feasibility and risk reduction research experiments on the critical components: (a) micro-cryogenerators; (b) micro-turbo-expanders; and (c) compact, high-effectiveness recuperators. In addition, the system design, including detailed assembly drawings and dimensioned part drawings, will be developed. Commercial Applications and Other Benefits as described by the awardee: The current market for cryocoolers with the one watt cooling capacity is several thousand units per year for (a) high-sensitivity radiation detectors and imagers, (b) targeting devices, and (c) MRI and NMR superconducting magnets. In addition, two very large markets may develop in the next century: liquid hydrogen fuel refrigeration and cryogenic microprocessors for advanced engineering workstations. _