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

Patent metadata

Field	Value
Publication number	US-2021284548-A1
Application number	US-202117303276-A
Country	US
Kind code	A1
Filing date	May 26, 2021
Priority date	Sep 25, 2014
Publication date	Sep 16, 2021
Grant date	—

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

1 . A refrigerator for accumulating an ultralow temperature of 20 K or lower, comprising: at least one cold accumulating vessel,
wherein a rare earth cold accumulating material particle in the cold accumulating vessel is packed, 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 refrigerator 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 according to claim 1 in a content of 50% by mass or more and 100% by mass or less.

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

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

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

6 . The refrigerator 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 the cold accumulating vessel, and wherein the rare earth cold accumulating material particles are packed in the stage of regenerator material-filled zones.

7 . The refrigerator 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 refrigerator 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 refrigerator according to claim 6 ,
wherein an inside of the cold accumulating vessel is divided into two stages, wherein a group of HoCu 2 particles is filled as a first group of cold accumulating material particles, and wherein a group of rare earth cold accumulating material particles composed of a rare earth oxides or a rare earth acid sulfides is filled as a second group of cold accumulating material particles.

10 . The refrigerator according to claim 6 ,
wherein an inside of the cold accumulating vessel is divided into three stages, wherein a group of lead cold accumulating material particles is filled as a first group of cold accumulating material particles, and wherein a group of HoCu 2 particles is filled as a second cold accumulating material particles, and wherein a group of rare earth cold accumulating material particles composed of rare earth oxides or rare earth acid sulfides is filled as a third group of cold accumulating material particles.

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

12 . The refrigerator according to claim 1 , wherein the rare earth cold accumulating particle has an average particle size of 100 to 500 μm is packed in the cold accumulating vessel.

13 . The refrigerator 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%.

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

15 . The refrigerator 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 wherein “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.

16 . The refrigerator 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).

17 . A pulse tube refrigerator for accumulating an ultralow temperature of 20 K or lower, comprising: a first cooling stage and a second cooling stage,
wherein Cu mesh cold accumulating material is filled in the first cooling stage; wherein a filling space of the second cooling stage is partitioned into a first to a third filling spaces; wherein a group of lead cold accumulating material particles is filled into the partitioned first filling space; wherein a group of HoCu 2 cold accumulating material particles is filled into the partitioned second filling space; wherein a group of cold accumulating material particles is filled 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.

18 . The pulse tube refrigerator according to claim 17 , wherein the pulse tube refrigerator is a 4 K pulse tube refrigerator.

19 . A superconducting magnet including the refrigerator according to claim 1 .

20 . An MRI including the refrigerator according to claim 1 .

21 . An NMR including the refrigerator according to claim 1 .

22 . A cryopump including the refrigerator 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

• C01F17/34

  Aluminates, e.g. YAlO3 or Y3-xGdxAl5O12 · CPC title

• F25B9/00

  Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point · 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