Abstract A new magnetic regenerator material for sub-4 K cryocoolers has been studied. Some rare-earth oxide magnetic materials have the potential to provide a high heat capacity below 4 K. From surveying the garnets and perovskites rare-earth oxides, we have found that a perovskite GdAlO3 (GAP) has a very large volumetric heat capacity below 4 K and it is useful as a regenerator material. Fine particles of the polycrystal GAP between 100 and 500 μm sizes were fabricated by a chemical process. The measured heat capacity of the fabricated GAP was in good agreement with that of single crystal material, and the magnetic field dependence was negligible when applying a magnetic field of 1 T. From thermal conductivity measurements, GAP was found to have 3 ∼10 times higher thermal conductivity than that of SUS from 5 K to 20 K. A refrigeration test was also done with a 4 K pulse tube refrigerator operating with a 3.3 kW compressor. The cooling power was increased remarkably from 165 mW to 250 mW at 4.2 K when using GAP in the lower temperature portion of the 2nd-stage regenerator. The minimum no-load temperature was lowered from 2.9 K to 2.5 K. There was an optimum value for the volumetric ratio of GAP that corresponded to the best cooling performance.


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    Title :

    New Regenerator Material for Sub-4 K Cryocoolers


    Contributors:
    Numazawa, T. (author) / Arai, O. (author) / Sato, A. (author) / Fujimoto, S. (author) / Oodo, T. (author) / Rang, Y. M. (author) / Yanagitani, T. (author)

    Published in:

    Publication date :

    2002-01-01


    Size :

    9 pages




    Type of media :

    Article/Chapter (Book)


    Type of material :

    Electronic Resource


    Language :

    English




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