Refrigerator including rare earth cold accumulating material particles, and superconducting magnet, inspection device and cryopump using same
AssigneesKabushiki Kaisha Toshiba, Toshiba Materials Co., Ltd.
InventorsKatsuhiko Yamada, Keiichi Fuse
Life of this patent
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Abstract
A refrigerator is provided, including rare earth cold accumulating material particles filled in a cold accumulating vessel. The rare earth cold accumulating material particles are a rare earth oxide or a rare earth oxysulfide. The rare earth cold accumulating material particles define 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. In an arbitrary cross-section of the rare earth cold accumulating material particles, a number of pores per a unit area of 10 μm×10 μm is 20 to 70.
Claims22
A refrigerator for accumulating an ultralow temperature of 20 K or lower, comprising:
- at least one cold accumulating vessel,
- wherein rare earth cold accumulating material particles are filled in the cold accumulating vessel,
- wherein the rare earth cold accumulating material particles consist essentially of a rare earth oxide or a rare earth oxysulfide,
- wherein the rare earth cold accumulating material particles define 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 particles, a number of pores per a unit area of 10 μm×10 μm is 20 to 70.
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 a Cu mesh cold accumulating material is filled in the first cooling stage,
- wherein a filling space of the second cooling stage is partitioned into first, second and third filling spaces,
- wherein a group of lead cold accumulating material particles is filled into the partitioned first filling space,
- wherein a group of HoCu2 cold accumulating material particles is filled into the partitioned second filling space,
- wherein a group of rare earth cold accumulating material particles is filled into the partitioned third filling space,
- wherein the rare earth cold accumulating material particles consist essentially of a rare earth oxide or a rare earth oxysulfide,
- wherein the rare earth cold accumulating material particles define 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 particles, a number of pores per a unit area of 10 μm×10 μm is 20 to 70.
Dependencies are inferred from the claim text.