TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)
Online ISSN : 1880-0408
Print ISSN : 0389-2441
ISSN-L : 0389-2441
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Volume 15, Issue 5
Displaying 1-5 of 5 articles from this issue
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  • [title in Japanese]
    K. OHSHIMA
    1980 Volume 15 Issue 5 Pages 261
    Published: October 30, 1980
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2221/jcsj.15.261
    JOURNAL FREE ACCESS
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  • Oscillatory Phenomena in Very Low Temperature Cooling Media-Part 2
    Sakutaro TOMIYAMA, Noriharu TAMADA
    1980 Volume 15 Issue 5 Pages 262-269
    Published: October 30, 1980
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2221/jcsj.15.262
    JOURNAL FREE ACCESS
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    The types of the oscillations of very low temperature circulation systems are reviewed.
    Despite the considerable success of the techniques which were developed in '60s to analyse the dynamical and transient behaviors of cryogenic systems, the incompetence thereof to predict exactly the modes of oscillations and instabilities of the He systems operated around the critical point now becomes gradually aparent. The chief aim of this review is to clarify where they fail and suggest how we can save them.
    The evidences which show the abnormally swift diffusion of enthalpy along supercritical He channels are presented. The relationship between oscillation modes and inhomogenuities of temperature, density and velocity of He coolant is stressed.
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  • Study on Superconducting Magnets Cooled by Superfluid Helium-Part 2
    Hisayasu KOBAYASHI, Ko YASUKOCHI
    1980 Volume 15 Issue 5 Pages 270-277
    Published: October 30, 1980
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2221/jcsj.15.270
    JOURNAL FREE ACCESS
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    This paper continues from part-1 to study on the cooling of superconducting magnets by the use of He II. In this part, the fact that the cooling efficiency in He II increases drastically by pressurizing the liquid is illustrated by examples. We also give examples in which the performances of magnet quenching currents and minimum propagating currents were improved by He II. On the other hand, we envisage several problems of instability on the lowered temperature region, such as the Kapitza resistance between the stabilizing material and the superconductor, and the a.c. loss caused by increased magnetization. The demerits, however, are probably overcome by the excellent cooling abilities of He II, especially of the pressurized He II. Finally, basic ideas of conceptual designs of superconducting troidal field coils in Torus II Supra (France) and NUMAK (U.S.A.) projects are introduced focusing on the cooling manner by means of the subcooled He II at 1.8K.
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  • Differential Pressure Flow Meter of Cryogenic Fluids
    Mineo TANAKA, Toyoichiro SHIGI
    1980 Volume 15 Issue 5 Pages 278-282
    Published: October 30, 1980
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2221/jcsj.15.278
    JOURNAL FREE ACCESS
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    Two small venturi flow meters of the JIS standard size have been made to test their applicability for helium gas at low temperatures over a wide renge of the Reynold's number.
    The experimental results are consistent with the turburent flow theory for the Reynold's number larger than 8×104.
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  • Pool Boiling Heat Transfer to Saturated Liquid Helium
    Hideo TSURUGA, Kazuo ENDOH
    1980 Volume 15 Issue 5 Pages 283-287
    Published: October 30, 1980
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2221/jcsj.15.283
    JOURNAL FREE ACCESS
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    Steady and transient heat transfer from a horizontal surface to liquid helium was measured from convection to film boiling region at bulk liquid temperatures between 2.5 and 5.1K. The test copper cylinder was insulated with vacuum, except the flat heat transfer surface of 20mm in diameter. The influence of four different surface treatment, three kinds of finish and coating over the same copper sample on maximum heat flux was also investigated in the pressure range of 0.046<P/Pc<0.92 corresponding to the temperature from 2.5 to 5.1K.
    Experimental results obtained in the developed nucleate boiling region shifted to larger ΔT value than the reported data compared at the same heat flux and nucleate boiling data were correlated with a modified Rohsenow equation. The film boiling data were correlated well with Rayleigh number and Nusselt number based upon Laplace reference length. Three kinds of dynamic temperature variation were noted corresponding to three boiling regions for the step change of heat input. The peak of the maximum heat flux curves shifted toward 0.5Pc for the two more rough sufaces. Maximum heat flux was found to decrease with surface coating for the polished surface.
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