Cryocoolers 8 pp 823-833 | Cite as

Variable Temperature Thermal Conductivity and Conductance Measurements Using a Gifford-McMahon Cryocooler

  • J. D. Walters
  • T. H. Fikse
  • T. L. Cooper

Abstract

The U.S. Navy is pursuing the design and fabrication of a superconducting magnet system cooled by closed cycle cryogenic refrigerators; no liquid helium will be used at all to cool the superconducting magnet. Well characterized superconducting magnet materials and thermally efficient interfaces between cryocoolers and the magnet, current leads, and radiation shields are critical because of the limited cooling capacity of cryocoolers being considered. In order to determine the thermal conductivity or conductance of several magnet composites and interfaces, respectively, a variable temperature apparatus has been developed which incorporates a Gifford-McMahon(GM) cryocooler. High heat capacity neodymium is used in the GM’s second stage regenerator and in a thermal filter used to smooth normally occurring temperature oscillations inherent to GM cryocoolers. In addition to good thermal performance, connections between the leads and coolers, and the magnet and coolers must be good electrical isolators to protect against damaging high voltages developed during magnet quenches. Measurements of thermal conductivity and conductance are made in the range of 6.0 K–35.0 K. This range is chosen to encompass the probable operating temperatures of conductively cooled NbTi, Nb3Sn, and high Tc magnets. Design, fabrication, and general operation of the thermal conductivity measuring apparatus are presented and discussed.

Keywords

Chrome Helium Epoxy Assure Ruthenium 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    General Electric Preparing to Announce Extraordinary New MRI System, Superconducting News. Vol. 6, No 16, Jan 26, 1994, Superconductivity Publications, Inc.(1994).Google Scholar
  2. 2.
    Y. Matsubara, K. Kanbara, T. Munekata, and K. Yasukochi, “Indirect Conduction Cooling of Superconducting Magnet”. Advances in Cryogenic Engineering, Vol. 27 (1982), 367–374.Google Scholar
  3. 3.
    Y. Yamada, J. Sakuraba, T. Hasebe, C.K. Chong, M. Ishihara, and K. Watanabe, “High-Tc Oxide Current Leads and Superconducting Magnet Using No Liquid Helium”, To be Published in the Proceedings of the Cryogenic Engineering Conference held in Albuquerque, New Mexico, 1993.Google Scholar
  4. 4.
    S. Hayashi, T. Egi, T. Hase, and K. Shibutani, “Oxide Superconductor Magnet Operated Near 20K”, To be Published in the Proceedings of the Cryogenic Engineering Conference held in Albuquerque, New Mexico, 1993.Google Scholar
  5. 5.
    J.R. Rowe, J.A. Hertal, J.A. Barclay, C.R. Cross, J.R. Trueblood, and D.D. Hill, “Conductively Cooled Nb3Sn Magnet System for Magnetic Refrigerator”, IEEE Transactions on Magnetics. Vol. 27, No. 2, March 1991, pp. 2377–2380.ADSCrossRefGoogle Scholar
  6. 6.
    K. Watanabe, S. Awaji, Y. Yamada, J. Sakuraba, F. Hata, C.K. Chong, T. Hasebe, and M. Ishihara, “Characteristics of a High Temperature Operation In a Conduction Cooled (Nb, Ti)3Sn Superconducting Magnet”, To be Published in the Proceedings of the Cryogenic Engineering Conference held in Albuquerque, New Mexico, 1993.Google Scholar
  7. 7.
    J. Chafe, G. Green, and R.C. Riedy, “Neodymium Regenerator Test Results in a Standard Gifford-McMahon Refrigerator”, Proceedings of the 7th International Cryocooler Conference. Albuquerque, New Mexico (1993).Google Scholar
  8. 8.
    R. Plambeck, N. That, and P. Sykes, “A 4 K Gifford-McMahon Refrigerator For Radio Astronomy”, Proceedings of the 7th International Cryocooler Conference, April 1993, pp 401-415.Google Scholar
  9. 9.
    The Art of Electronics, second Ed., Horowitz and Hill, Cambridge University Press(1991).Google Scholar
  10. 10.
    PSI-Plot Software version 2.10, Poly Software International(1993).Google Scholar
  11. 11.
    L.L. Sparks and R.L. Powel, “Low Temperature Thermocouples: KP, “normal” silver, and copper versus Au-0.02 at% Fe and Au-0.07 at% Fe”. J. Res. Nat. Bur. Std. 76a. 263 (1972).Google Scholar
  12. 12.
    SigmaPlot Scientific Graph System, Jandel Scientific, Version 5.0(1992).Google Scholar
  13. 13.
    Handbook on Materials for Superconducting Machinery, Metals and Ceramic Information Center, Battelle Columbus Laboratories, ARPA order number 2569, Contract number CST-8303(1975).Google Scholar
  14. 14.
    Thermal Conductivity of Solids At Room Temperature and Below. NBS Monograph 131, U.S. Dept. of Commerce, p. 257(1973).Google Scholar
  15. 15.
    Cryocomp, Computer Software, Cryodata Inc., Version 2.0, Nov. 1993.Google Scholar
  16. 16.
    A. Yucel and J.R. Maddocks, “Thermal Conductivities of Commercially Available 21-6-9 Stainless Steel”, Presented at the 1993 Cryogenic Engineering Conference in Albuquerque, New Mexico.Google Scholar
  17. 17.
    Materials at Low Temperatures. Ed. R.P. Reed and A.F. Clark, American Society for Metals, 144-154.Google Scholar

Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • J. D. Walters
    • 1
  • T. H. Fikse
    • 1
  • T. L. Cooper
    • 1
  1. 1.Annapolis DetachmentCDNSWCAnnapolisUSA

Personalised recommendations