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Cryocoolers 8 pp 517-524 | Cite as

Development Status of a 2.5 K – 4 K Closed-Cycle Cooler Suitable for Space Use

  • A. H. Orlowska
  • T. W. Bradshaw
  • J. Hieatt

Abstract

Temperatures below 2.5 K have been reached in a continuously operating closed cycle cooler that has been engineered for space applications. This cooler is a modification of a 4 K cryocooler that consists of a two-stage Stirling cycle precooler with a closed cycle Joule-Thomson (JT) stage. The Stirling cycle precooler and the compressors for the JT system incorporate all the long life features of the Oxford/RAL single stage coolers which have been flown successfully. Some modifications have been made to the original development model 4 K refrigerator; this paper reports on the testing and performance of the cooler. Measurements of the change in performance of the two stage cooler with compressor-displacer separation distance are presented.

4He is used in the JT system for temperatures around 4 K and 3 He is used below 3 K. Different JT expansion orifices are used to optimise the cooler at 4 K and 2.5 K giving flow rates of about 3 mg/s and 1 mg/s respectively. For operation at the lower temperatures the reduced flow enables a lower pressure (and hence temperature) to be maintained on the low pressure side of the expansion orifice.

Under no-load conditions and with no gas in the JT system the precooler reaches a base temperature of 11.3 K. The JT system provided over 11 mW of cooling at 4.5 K. With the smaller orifice and using 3 He a temperature of 2.46 K was achieved with a heat load of over 3 mW. The input power to the cooler was approximately 126 W. The temperature stability of the system at about 2.5 K was better than 40 mK over a 72 hour period.

Keywords

Heat Load Base Temperature Cooling Power Thermodynamic Cycle Total Input Power 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    under ESA contract 7198/MNL/MA(SC).Google Scholar
  2. 2.
    Bradshaw, T. W., Orlowska, A. H., “Mechanical cooling systems for use in space”. Proc. Instn Mech Engrs. vol.207 (1993) 21–25.Google Scholar
  3. 3.
    Bradshaw, T. W., Orlowska, A. H., and Hieatt, J. “Development status of a 2.5 K–4 K closed cycle cooler suitable for space use” Paper presented at the 24th International Conference on Environmental systems and 5th European Symposium on Space Environmental Control systems, Friedrichshafen, Germany 1994.Google Scholar

Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • A. H. Orlowska
    • 1
  • T. W. Bradshaw
    • 1
  • J. Hieatt
    • 1
  1. 1.Rutherford Appleton LaboratoryChilton, Didcot, OxonUK

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