IIR document

Application of cryocooler in the ultra-low temperature refrigeration.

Author(s) : ZHAO Z., JIRMANUS M. N., BOBB L., et al.

Summary

The paper presents two examples of cryogen-free ultra-low temperature cryostats that use mechanical cryocoolers to provide the necessary refrigeration. The first one is a cryogen-free He-3 cryostat using a two-stage Gifford-McMahon (G-M) cryocooler for He-3 condensation. After the He-3 gas is condensed, an internal charcoal sorption pump is used to pump the He-3 pot down below 300 mK. The second example is a cryogen-free two-stage Adiabatic Demagnetisation Refrigerator (ADR) using a 4 K pulse tube cryocooler. Gallium Gadolinium Garnet (GGG) and Ferric Ammonium Alum (FAA) paramagnetic pills were used for the first and second stage of the ADR, with Kevlar string supports for each stage. The FAA stage reaches a base temperature below 50 mK, and remains below 100 mK for more than two days. The performance of this cryocooled ADR is better (lower base temperature and longer hold time below 100 mK) than the equivalent liquid helium-based system. Design and performance details of the systems are discussed.

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Details

  • Original title: Application of cryocooler in the ultra-low temperature refrigeration.
  • Record ID : 2004-0998
  • Languages: English
  • Source: 21st IIR International Congress of Refrigeration: Serving the Needs of Mankind.
  • Publication date: 2003/08/17

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