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Rare-earth regenerator material particles, and group of rare-earth regenerator material particles, refrigerator and measuring apparatus using the same, and method for manufacturing the same

  • US 10,385,248 B2
  • Filed: 07/05/2018
  • Issued: 08/20/2019
  • Est. Priority Date: 08/25/2009
  • Status: Active Grant
First Claim
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1. A Gifford MacMahon type (GM) refrigerator for accumulating an extremely low temperature cold, comprising:

  • a vacuum chamber;

    an external cylinder provided so as to be disposed in the vacuum chamber, the external cylinder enclosing an inner space;

    at least one regenerator container for accumulating cold which is arranged at the inner space inside the external cylinder;

    a seal ring installed between the external cylinder and the regenerator container;

    an expanding chamber formed between the external cylinder and the regenerator container;

    a compressor for compressing a cooling medium gas; and

    a group of regenerator material particles packed in the regenerator container;

    wherein the group of regenerator material particles have an average particle size of 0.045 to 3 mm,wherein a proportion of particles having a ratio of a long diameter to a short diameter of 2 or less is 90% or more by number, a proportion of particles having a depressed portion having a length of 1/10 to ½

    of a particle circumferential length of a particle on a particle surface is 30% or more by number and wherein the depressed portion has a depth of 1/10 or less of a particle diameter.

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