A Self-Actuated Thermal Switch for Operation with Redundant Mechanical Refrigerators
The development of a thermal switch based on dissimilar materials is described. The switch was developed for use with redundant refrigerators for cooling a gamma-ray detector. It contains no “moving” parts, requires no actuation gas, and is passively switched from off to on or on to off solely by the cooling or warming of the refrigerator cold tip.
The switch has been found to be highly reliable while operating down to 80 K (with operation to colder temperature also being posible with design). Four of these switches have been built and tested with completely satisfactory results. Switching ratios of approximately 300 (which include the material resistance of flexible couplings) have been attained for this design, with much higher switching values being possible. This paper describes the switch design and test results.
KeywordsPlat INUM Molybdenum Refrigeration Fiberglass
Unable to display preview. Download preview PDF.
- 1.Personal communication with A. Daniels, Philips Laboratories, Briarcliff Manor, N.Y.Google Scholar
- 2.T. C. Nast and D. D. Murray, “Orbital Cryogenic Cooling of Sensor Systems,” AIAA Paper No. 76–979, presented at AIAA Technical Specialist Conference, Pasadena, California, October 1976Google Scholar
- 3.L. Naes and T. Nast, Long-Life Orbital Operation of Stirling Cycle Mechanical Refrigerators, Proc. of the Society of Photo-Optical Inst. Engr. 245(23):126(1980).Google Scholar
- 4.T. Nast, G. Bell, and C. Barnes, Development of Gas Gap Cryogenic Thermal Switch, in “Advances in Cryogenic Engineering” Vol 27, Plenum Press, New York (1982), p. 117.Google Scholar
- 5.M. M. Yovanovich and A. Hegazy, “An Accurate Universal Contact Conductance Correlation for Conforming Rough Surfaces with Different Micro-Hardness Profiles,” AIAA-83-1434, June 1–3, 1983, AIAA 18th Thermophysics Conference.Google Scholar