A111D3 DLbSbfi '^*™illiinLi™.?I'!},!:'.9i!'SP.S&.^ R.I.C. «KW3t??..„ SPECIAL PUBLICATION 508 U.S. DEPARTMENT OF COMMERCE / National Bureau of Standards 1 osea- 0 Small l7Q tioMl Bureau of Staruiards MAY 1 i 1978 ^ Applications of Closed-Cycle Cryocoolers to ^0 Small Superconducting Devices Proceedings of a Conference Held at the National Bureau of Standards, Boulder, Colorado October 3-4, 1977 Edited by James E. Zimmerman and Thomas M. Flynn Cryogenics Division Institute for Basic Standards National Bureau of Standards Boulder, Colorado 80303 Sponsored by National Bureau of Standards and Office of Naval Research Arlington, Virginia 22217 U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary Dr. Sidney Harman, Under Secretary Jordan J. Baruch, Assistant Secretary for Science and Technology NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director Issued April 1978 Library of Congress Catalog Card Number: 78-606017 National Bureau of Standards Special Publication 508 Nat. Bur. Stand. (U.S.) Spec. Publ. 508, 238 pages (Apr. 1978) CODEN. XNBSAV U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1978 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20434 Stock No 003-003-01910-1 Price $4.25 (Add 25 percent additional for other than U.S. mailing). ABSTRACT This document contains the proceedings of a meeting of specialists in small superconducting devices and in small cryogenic refrigerators. Industry, Government, and academia were represented at the meeting held at the National Bureau of Standards (NBS) on October 3 and 4, 1977« The purpose of the meeting was to define the refrigerator requirements for small superconducting devices and to determine if small cryogenic refrigerators that are produced in relatively large quantities can be adapted or developed to replace liquid helium as the cooling medium for the superconducting devices. Because the focus was on small superconducting devices, the discussion was primarily limited to refrigerators with capacities from zero up to a watt or two in the temperature range of 2 to 20 K. The meeting was jointly sponsored by the Office of Naval Research (ONE) and NBS. Key words: Cryo coolers; Refrigeration; Superconducting devices. iii Library of Congress Catalog Card Number: 78-606017 National Bureau of Standards Special Publication 508 Nat. Bur. Stand. (U.S.) Spec. Publ. 508. 238 pages (Apr. 1978) CODEN: XNBSAV U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1978 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, B.C. 20434 Stock No 003-003-01910-1 Price $4.25 (Add 25 percent additional for other than U.S. mailing). ABSTRACT This document contains the proceedings of a meeting of specialists in small superconducting devices and in small cryogenic refrigerators. Industry, Government, and academia were represented at the meeting held at the National Bureau of Standards (NBS) on October 3 and 4» 1977. The purpose of the meeting was to define the refrigerator requirements for small superconducting devices and to determine if small cryogenic refrigerators that are produced in relatively large quantities can be adapted or developed to replace liquid helium as the cooling medium for the superconducting devices. Because the focus was on small superconducting devices, the discussion was primarily limited to refrigerators with capacities from zero up to a watt or two in the temperature range of 2 to 20 K. The meeting was jointly sponsored by the Office of Naval Research (ONR) and NBS. Key words: Cryocoolers; Refrigeration; Superconducting devices. iii " TABLE OF CONTENTS Page 1. "Introductory Remarks and Summary," by R. Brandt, A. Silver and J.E. Zimmerman 1 2. "Refrigeration Fundamentals," by R. Radebaugh 7 3. "Concepts for Cooling Small Superconducting Devices Using Closed- Cycle Regenerative Refrigerators," by R.C. Longsworth 45 4. "Operation of a SQUID in a Very Low-Power Cryocooler," by J.E. Zimmerman and R. Radebaugh 5. "Shuttle Heat Transfer in Plastic Displacers at Low Speeds," by R. Radebaugh and J.E. Zimmerman 67 6. "Scaling of Miniature Cryocoolers to Microminiature Size," by W.A. Little 75 7. "Small Magnetic Refrigerators to Pump Heat from Helium Temperatures to above 10 K," by W.A. Steyert 81 8. "Electrocaloric Refrigeration for the 4-20 K Temperature Range," by R. Radebaugh ^3 9. "One Million Hours at 4.5 Kelvin," by W.H. Higa and E. Wiebe 10. "Design Compromises in the Selection of Closed-Cycle Cryocoolers," by F.F. Chellis ""09 11. "Magnetic and Vibrational Characteristics of a Closed Cycle Refrigerator," by J.E. Cox and S. A. Wolf "1 23 lii '12. "Closed-Cycle Refrigerator for a Superconducting Susceptometer, by D.A. Vincent I^l 13. "Cryogenic Applications of Closed-Cycle Mechanical and Adsorption Refrigeration," by W.H. Hartwig ^35 14. "Cryogenic Cooling Requirements of Photoconductive Infrared Detectors for Orbiting Astronomical Telescopes," by J.W. Vorreiter and C.R. McCreight ''^3 " TABLE OF CONTENTS, continued Page 15. "Cooling of Josephson MM- and SubMM-Wave Systems: Requirements, Results and Applications," by J. Edrich 159 16. "Progress Report on High-T^ Superconducting Devices," by M.R. Beasley 167 17. "Application of SQUID Detectors in Biomagnetism, by S.J. Williamson and L. Kaufman 177 18. "Cryogenic Techniques and Geophysical Measurements," by W.D. Stanley 205 19. "Cryocoolers for Use with Superconducting Instruments: Some Estimates of Requirements," by M.B. Simmonds 207 20. "Refrigerator Requirements for Potential Josephson Data Processing Systems," by B.J.C. van der Hoeven, Jr. and W. Anacker 213 21. "Liters, Kilograms, Watts and Seconds: Design Goals for a Refrigerator for Use with Superconductive Systems," by M. Nisenoff 221 22. "Potential Scientific Uses of Cryogens in Space in the Temperature Range from 1 mK to 10 K," by E. Tward 227 23. "Josephson Voltage Standards - An Application for Cryocoolers?" by L.B. Holdeman and C.C. Chang 243 24. Photograph of Delegates 247 25. Identification Page 248 26. List of Delegates with Addresses 249 DISCLAIMER Papers by non-NBS authors have not been reviewed or edited by NBS. Therefore, the National Bureau of Standards accepts no responsibility for comments or recommendations con- tained therein. vi INTRODUCTORY REMARKS AND SUMMARY Richard Brandt Office of Naval Research Pasadena, California 91106 Arnold Silver Aerospace Corporation Los Angeles, California 90009 James Zimmerman National Bureau of Standards Boulder, Colorado 80203 1 1 INTRODUCTORY REMARKS AND SUMMARY R. Brandt, A. Silver and J. Zimmerman This document contains the proceedings of a meeting of specialists in small supercon- ducting devices and in small cryogenic refrigerators. Industry, Government, and academia were represented at the meeting held at the National Bureau of Standards (NBS) on October 3 and 4, 1977. The purpose of the meeting was to define the refrigerator requirements for small superconducting devices and to determine if small cryogenic refrigerators that are produced in relatively large quantities can be adapted or developed to replace liquid helium as the cooling medium for the superconducting devices. Because the focus was on small superconducting devices, the discussion was primarily limited to refrigerators with capacities from zero up to a watt or two in the temperature range of 2 to 20 K. The meeting was jointly sponsored by the Office of Naval Research (ONR) and NBS, and was organized by Edgar Edelsack of ONR (who for personal reasons was unable to attend), Professor Little of Stanford Univer- sity, and Tom Flynn, Ray Radebaugh and Jim Zimmerman of NBS. Superconducting devices are finding applications in many areas, including biomedical research, geophysical measurements, metrology, electromagnetic radiation detection, digital signal processing and computing. The customary way to provide the required low-temperature environment is to immerse the device in a bath of liquid helium. This procedure has many advantages; in particular, the liquid helium bath is mechanically and magnetically quiet, thermally stable even with large heat loads, and not subject to mechanical breakdown, whereas existing cryogenic refrigerators suffer from many of these problems. Furthermore, liquid helium is readily available commercially and is relatively inexpensive in the present supply/ demand situation. For these reasons, considerable efforts have been made to optimize the design of liquid helium dewars for specific applications. This approach is satisfactory at present while the various application possibilities are being explored. However, if super- conductive instruments are ever to have widespread use, it will be necessary to incorporate cryocoolers which can be operated by ordinary technicians rather than cryogenic specialists. The papers contained herein cover a broad range of technologies, from classical refri- geration techniques at one extreme, to recent exotic applications of superconductivity such as magnetic measurements of earth conductivity and of human brain activity at the other. It was precisely the purpose of the meeting to bring together those of such diverse interests. It is hoped that face-to-face encounters between the users and the producers of low tempera- ture will stimulate thought and development of small superconducting and other cryogenic instrumentation which can be put into operation by the simple expedient of throwing a switch. Since the facilities available for the meeting did not permit an open invitation to everyone who might have wished to attend, it is the purpose of this document to make avail- able to a wider audience most of what was discussed. It contains most of the papers that were presented orally at the meeting, as well as a paper by Holdeman and Chang, not presented at the meeting, describing recent development of a simplified Josephson dc voltage standard. Papers ROt included (no manuscripts having been submitted) are one by Durenec on a miniature ultra-quiet dual-reciprocating compressor for small cryocoolers, one by Goodkind on his notable work with a gravimeter (mentioned briefly by Stanley in his paper), one by Goree on the use of small cryocoolers to extend the operating time of liquid helium dewars, and others.