Ultra-Low Temperature Cryogen-Free Refrigerator

P.A. Bromiley, I.D. Hepburn, A. Smith, N. Kerley and W. Duncan

Sixth European Symposium on Space Environmental Control Systems, Noordwijk, The Netherlands, 1997.

Details of a refrigerator (dADR) under development which can provide cooling to 0.05 K from a 5-4 K environment in a two stage system and 0.005K in a three stage system are presented. The refrigerator is a new form of adiabatic demagnetization refrigerator which has enabled a factor 5 reduction in the required magnetic field enabling it to be considered for use by mechanical cryocoolers. The refrigerator requires a 1 Tesla magnetic field, has an estimated mass of 21 Kg (including 7 Kg of electronics) and will provide a cooling power of 1 mW at 0.1K for 17 hours when operated from a 4.3K base plate and with a recycle time of 1 to 7 hours. The refrigerator is constructed from known technology and is independent of the cooling system used to provide the 5-4K environment. Coupling of the dADR to a mechanically cooled environment offers consumable free operation thereby very considerably extending operational lifetime as compared with cryogenic missions. This refrigerator offers a simple, easily integrable, cryogenic sub-system composed of purely mechanical and electrical interfaces.

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