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Measurement of Thermal Conductance

  • M. Kuchnir
Part of the Advances in Cryogenic Engineering book series (ACRE, volume 22)

Abstract

The 6-m long, 45-kG, warm-iron superconducting magnets envisioned for the Energy Doubler stage of the Fermilab accelerator require stiff supports with minimized thermal conductances in order to keep the refrigeration power reasonable. The large number of supports involved in the system required a careful study of their heat conduction from the room temperature wall to the intercepting refrigeration at 20 K and to the liquid helium. For this purpose the thermal conductance of this support was measured by comparing it with the thermal conductance of a copper strap of known geometry. An association of steady-state thermal analysis and experimental thermal conductivity techniques forms the basis of this method. An important advantage is the automatic simulation of the 20 K refrigeration intercept by the copper strap, which simplifies the apparatus considerably.

Keywords

Copper Block Heat Leak Stiff Support Thermal Circuit Fermi National Accelerator Laboratory 
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.

Notation

Ql

heat per unit time electrically delivered to the room temperature tube

Q2

heat per unit time electrically delivered to the shield intercept

O3

heat per unit time electrically delivered to the reference copper strap

QS

heat per unit time flowing from the support into the intercept

QCu

heat per unit time flowing through the copper strap

QH

heat per unit time flowing through R 2

R1

thermal resistance of the support between room temperature tube and 20 K shield intercept

R2

thermal resistance of the support between the shield intercept and the copper block nea 4.2 K

R3

thermal resistance of the copper strap (reference heat resistor)

TH

temperature of the copper block (close to 4.2 K)

TR

temperature the the room temperature tube

TS

temperature of the shield intercept (close to 20 K)

T’S

temperature of the free end of the reference copper strap

Greek Symbols

Δ1

radiation heat leak per unit time into the room temperature tube

Δ2

radiation heat leak per unit time into the shield intercept

Δ3

radiation heat leak per unit time into the free end of the reference copper strap

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References

  1. 1.
    G. E. Childs, L. J. Ericks, and R. L. Powell, “Thermal Conductivity of Solids at Room Temperature and Below,” NBS Monograph 131, (1973), p. 6.Google Scholar
  2. 2.
    M. Kuchnir and P. Sanger, IEEE Trans. Nucl. Sci. NS-22(3):1183 (1975).CrossRefGoogle Scholar
  3. 3.
    F. R. Schwartzberg, R. G. Herzog, S. H. Osgood, and M. Knight, Cryogenic Materials Data Handbook, Vol. 2, National Technical Information Service, Springfield, Virginia (1970), p. 418.Google Scholar

Copyright information

© Springer Science+Business Media New York 1977

Authors and Affiliations

  • M. Kuchnir
    • 1
  1. 1.Fermi National Accelerator LaboratoryBataviaUSA

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