Rare earth cold accumulating material particles, and refrigerator, superconducting magnet, inspection device and cryopump using same

Patent metadata

Field	Value
Publication number	US-11136244-B2
Application number	US-201816182908-A
Country	US
Kind code	B2
Filing date	Nov 7, 2018
Priority date	Sep 25, 2014
Publication date	Oct 5, 2021
Grant date	Oct 5, 2021

Abstract

The present invention provides a rare earth cold accumulating material particle comprising a rare earth oxide or a rare earth oxysulfide, wherein the rare earth cold accumulating material particle is composed of a sintered body; an average crystal grain size of the sintered body is 0.5 to 5 μm; a porosity of the sintered body is 10 to 50 vol. %; and an average pore size of the sintered body is 0.3 to 3 μm. Further, it is preferable that the porosity of the rare earth cold accumulating material particle is 20 to 45 vol. %, and a maximum pore size of the rare earth cold accumulating material particle is 4 μm or less. Due to this structure, there can be provided a rare earth cold accumulating material having a high refrigerating capacity and a high strength.

First claim

The invention claimed is:

1. A method of manufacturing a refrigerator for accumulating an ultralow temperature of 20 K or lower, the method comprising the steps of:
providing a cold accumulating vessel; and
packing a rare earth cold accumulating material particle in the cold accumulating vessel;
wherein the rare earth cold accumulating material particle consists essentially of a rare earth oxide or a rare earth oxysulfide;
wherein the rare earth cold accumulating material particle is a sintered body;
wherein an average crystal grain size of the sintered body is 0.5 to 5 μm;
wherein a porosity of the sintered body is 10 to 50 vol %; wherein an average pore size of the sintered body is 0.3 to 3 μm; and
wherein in an arbitrary cross section of the rare earth cold accumulating material particle, a number of pores per a unit area of 10 μm×10 μm is 20 to 70.

2. The method according to claim 1 , wherein a group of the rare earth cold accumulating material particles packed in the cold accumulating vessel includes the rare earth cold accumulating material particles in a content of 50% by mass or more and 100% by mass or less.

3. The method according to claim 1 , wherein the refrigerator is a GM refrigerator.

4. The method according to claim 1 , wherein the refrigerator is a Stirling refrigerator.

5. The method according to claim 1 , wherein the refrigerator is a pulse tube refrigerator.

6. The method according to claim 1 , wherein two or more stages of cold accumulating material-filled zones are formed which are divided by a metal mesh material in at least one cold accumulating vessel, and the rare earth cold accumulating material particles are packed in at least one stage of regenerator material-filled zones.

7. The according to claim 6 , wherein the metal mesh material comprises a metal mesh member composed of copper or a copper alloy is packed.

8. The method according to claim 7 , wherein the method further comprises the step of packing the mesh material comprising a metal mesh member composed of copper or a copper alloy.

9. The method according to claim 1 , wherein the refrigerator is used for obtaining an ultralow temperature of 10 K or lower.

10. The method according to claim 1 , wherein the rare earth cold accumulating particle has an average particle size of 100 to 500 μm.

11. The method according to claim 1 , wherein a filling factor of the cold accumulating material particles in the cooling stage of a refrigerator falls within a range from 55 to 70%.

12. The method according to claim 1 , wherein the rare earth cold accumulating material particle has an aspect ratio of 2 or less.

13. The method according to claim 1 , wherein when L represents a perimeter length of a projection image of each of the cold accumulating material particles constituting a group of rare earth cold accumulating material particles, and A represents the actual area of the projection image, in the group of rare earth cold accumulating material particles, a proportion of the rare earth cold accumulating material particles having a shape factor R being represented by L 2 /4πA and exceeding 1.5 is 5% or less.

14. The method according to claim 1 , wherein the rare earth cold accumulating material particle comprises gadolinium aluminum oxide (GdAlO 3 ) or gadolinium oxysulfide (Gd 2 O 2 S).

15. A method of manufacturing a pulse tube refrigerator for accumulating an ultralow temperature of 20 K or lower, the method comprising the steps of:
filling a Cu mesh cold accumulating material in a first cooling stage;
partitioning a filling space of a second cooling stage into a first to a third filling spaces;
filling a group of lead cold accumulating material particles into the partitioned first filling space;
filling a group of HoCu 2 cold accumulating material particles into the partitioned second filling space; and
filling a group of cold accumulating material particles into the partitioned third filling space wherein the rare earth cold accumulating material particle consists essentially of a rare earth oxide or a rare earth oxysulfide;
wherein the rare earth cold accumulating material particle is a sintered body;
wherein an average crystal grain size of the sintered body is 0.5 to 5 μm;
wherein a porosity of the sintered body is 10 to 50 vol %; wherein an average pore size of the sintered body is 0.3 to 3 μm; and
wherein in an arbitrary cross section of the rare earth cold accumulating material particle, a number of pores per a unit area of 10 μm×10 μm is 20 to 70.

16. The method according to claim 15 , wherein the pulse tube refrigerator is a 4K pulse tube refrigerator.

17. A method of manufacturing a superconducting magnet provided with a refrigerator for accumulating an ultralow temperature of 20 K or lower, wherein the refrigerator is manufactured by the method according to claim 1 .

18. A method of manufacturing an MRI provided with a refrigerator for accumulating an ultralow temperature of 20 K or lower, wherein the refrigerator is manufactured the method according to claim 1 .

19. A method of manufacturing an NMR provided with a refrigerator for accumulating an ultralow temperature of 20 K or lower, wherein the refrigerator is manufactured by the method according to claim 1 .

20. A method of manufacturing a cryopump provided with a refrigerator for accumulating an ultralow temperature of 20 K or lower, wherein the refrigerator is manufactured through the method according to claim 1 .

Assignees

• Toshiba Kk
• Toshiba Materials Co Ltd

Inventors

• Yamada Katsuhiko
• Fuse Keiichi

Classifications

• H01F6/04

  Cooling · CPC title

• F25B9/14 Primary

  characterised by the cycle used, e.g. Stirling cycle · CPC title

• H01F6/003

  Methods and means for discharging superconductive storage (superconducting alloys C22C; static memories with superconducting elements G11C11/44; superconducting circuit breakers with contacts H01H33/004; superconducting switches for low power H03K17/92; superconducting material H10N60/00; power cryotons H10N60/355) · CPC title

• C09K5/14

  Solid materials, e.g. powdery or granular · CPC title

• F04B37/08

  by condensing or freezing, e.g. cryogenic pumps · CPC title