Control System for Temperatures and Liquid Level between 4.2° and 1°K

  • A. Elsner
  • G. Klipping
Part of the Advances in Cryogenic Engineering book series (ACRE, volume 14)


An earlier publication [1] describes a continuous open-cycle cooling process for liquid-helium cryostats which permits one to maintain a constant liquid level in the cryostat for any length of time for helium-I at temperature levels between the normal boiling point and the λ-point. In this process, the cryostat is refilled by means of a vent-gas cooled transfer tube which has an expansion valve at the exit surrounded by sintered metal. The expansion valve is regulated by means of an electric liquid-level controller. A control valve In the vent-gas pipe connected to a vacuum pump Is operated by a pressure control. The liquid level remains essentially stable even If the expansion valve Is placed only 1 cm above it. This process makes it possible to refill even very small volumes with helium. A temperature constancy of ΔT/T = 10-3 is also achieved, with this process.


Expansion Volume Liquid Level Breakthrough Point Aluminum Silicate Superfluid Helium 
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  1. 1.
    A. Eisner, G. Hildebrandt, and G. Klipping, in: Liquid Helium Technology, Inst. Int. du Froid, Annexe 1966–5 (1966), p. 143.Google Scholar
  2. 2.
    F. E. Hoare, L. C. Jackson, and N. Kurti, Experimental Cryophysics, Butterworths, London (1961), p. 155.Google Scholar

Copyright information

© Springer Science+Business Media New York 1969

Authors and Affiliations

  • A. Elsner
    • 1
  • G. Klipping
    • 1
  1. 1.Fritz Haber InstitutMax Planck GesellschaftBerlinWest Germany

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