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Dry dilution refrigerator with high cooling power.

Author(s) : UHLIG K.

Summary

The author presents the construction concept and cooling capacity measurements of a 3,4 He dilution refrigerator, which was pre-cooled by a commercial pulse tube refrigerator. No cryogens are needed for the operation of this type of cryostat. The condensation of the helium mash was done in an integrated Joule-Thomson circuit, which was part of the dilution unit. The composition of the dilution unit was standard, but its components (still, heat exchangers, mixing chamber) were designed for high 3He flow. For thermometry, calibrated RuO chip resistance thermometers were available. In order to condense the mixture before an experiment, the fridge was operated like a Joule-Thomson liquefier with a relatively high inlet pressure (4 bars), where the liquid fraction of the circulating 3,4He mixture was accumulated in the dilution unit. The condensation took about 2 hours, and after 2 more hours of running, the temperature of the mixing chamber approached its minimum temperature of 10 mK. The maximum flow rate of the fridge was 1 mmol/s, and the refrigeration capacity of the mixing chamber was 700 microW at 100 mK. High cooling capacity, ease of operation and reliability distinguish this type of milli-Kelvin cooler.

Details

  • Original title: Dry dilution refrigerator with high cooling power.
  • Record ID : 2008-1435
  • Languages: English
  • Publication date: 2007/07/16
  • Source: Source: Adv. cryog. Eng., Trans. CEC/AIP Conf. Proc./Proc. CEC, Chattanooga, Tennessee
    vol. 53; CP985; 1287-1291; fig.; 6 ref.

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