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 10,040,982 B2
• Filed: 12/05/2016
• Issued: 08/07/2018
• Est. Priority Date: 08/25/2009
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Materials Company Limited (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Materials Company Limited (Toshiba Corporation)
• Inventors: Yamada, Katsuhiko, Fuse, Keiichi
• Primary Examiner(s): Wartalowicz, Paul A
• Application Number:
  US15/369,546
• Publication Number:
  US 20170082323A1
• Time in Patent Office: 610 Days
• Field of Search: 505162
• CPC Class Codes: B22F 9/08 by casting, e.g. through sieves or in water, by atomising or spraying using electric discharge B22F9/14
• CPC Class Codes: B22F 9/10 using centrifugal force
• CPC Class Codes: B23P 15/26 heat exchangers or the like making heat exchangers by methods covered by other subclasses B21D53/02
• CPC Class Codes: C09K 5/041 for compression-type refrigeration systems
• CPC Class Codes: C09K 5/08 Materials not undergoing a change of physical state when used C09K5/16, C09K5/20 take precedence
• CPC Class Codes: C09K 5/14 Solid materials, e.g. powdery or granular
• CPC Class Codes: C22C 2202/02 Magnetic
• CPC Class Codes: F25B 2309/003 characterised by construction or composition of the regenerator
• CPC Class Codes: F25B 2309/1415 Pulse-tube cycles characterised by regenerator details
• CPC Class Codes: F25B 9/14 characterised by the cycle used, e.g. Stirling cycle
• CPC Class Codes: F25B 9/145 pulse-tube cycle
• CPC Class Codes: G01R 33/3804 Additional hardware for cooling or heating of the magnet assembly, for housing a cooled or heated part of the magnet assembly or for temperature control of the magnet assembly
• CPC Class Codes: G01R 33/3815 with superconducting coils, e.g. power supply therefor
• CPC Class Codes: H01F 1/015 Metals or alloys
• CPC Class Codes: Y10T 428/12014 having metal particles

Abstract

Provided is a group of rare-earth regenerator material particles having an average particle size of 0.01 to 3 mm, wherein the proportion of particles having a ratio of a long diameter to a short diameter of 2 or less is 90% or more by number, and the proportion of particles having a depressed portion having a length of 1/10 to ½ of a circumferential length on a particle surface is 30% or more by number. By forming the depressed portion on the surface of the regenerator material particles, it is possible to increase permeability of an operating medium gas and a contact surface area with the operating medium gas.

Claims

1. A refrigerator for accumulating an extremely low temperature cold, comprising:

a vacuum chamber;

an external cylinder disposed in the vacuum chamber, the external cylinder enclosing an inner space;

a first regenerator container for accumulating cold and a second regenerator container for accumulating cold which are arranged at the inner space inside of the external cylinder, the first regenerator container for accumulating a first cold generated at a first cooling stage, the second regenerator container for accumulating a second cold generated by further cooling the first cold at a second cooling stage,

a mesh-like member packed in the first regenerator container for accumulating cold, and

regenerator material particles packed in the second regenerator container, the regenerator material particles comprising a rare-earth metal and having 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 depth of 1/10 or less of a particle diameter, and the depressed portion has channel-shape or a hole-shape.

2. The refrigerator according to claim 1, wherein the extremely low temperature is lower than 10K.

3. The refrigerator according to claim 1, wherein the second group of regenerator material particles are arranged in one packing layer formed between mesh-like members which are disposed respectively at inner end portions of the second regenerator container.

4. The refrigerator according to claim 1, wherein the second group of regenerator material particles are arranged in a plurality of packing layers formed between a plurality of mesh-like members which are disposed within a space in the second regenerator container.

5. The refrigerator according to claim 1, wherein the second group of regenerator material particles comprising at least one element selected form a group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb).

6. The refrigerator according to claim 1, wherein the second group of regenerator material particles comprising at least one selected from the group composed of a rare-earth elemental of single substance, and alloy with Cu (including an intermetallic compound), a rare-earth with Ni (including an intermetallic compound), a rare-earth oxide (including a rare-earth complex oxide), and a rare-earth sulfide.

7. The refrigerator according to claim 1, wherein the second group of regenerator material particles comprising at least one selected from the group consisting of Nd, Er₃Ni, ErNi, HoCu₂, Gd₂O₃, and Gd₂O₂S.

8. A measuring apparatus, comprising a superconducting magnet comprising the refrigerator of claim 1.

9. The measuring apparatus of claim 8, which is at least one apparatus selected from the group consisting of an MRI and an NMR.

10. A cryopump, comprising a superconducting magnet comprising the refrigerator of claim 1.