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47 巻 , 12 号
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基礎講座
  • 村上 雅人
    47 巻 (2012) 12 号 p. 660-666
    公開日: 2013/01/31
    ジャーナル フリー
    This paper summarizes processing, properties and applications of bulk high-temperature superconductors based on RE-Ba-Cu-O (RE: rare earth elements). For practical applications, one needs to grow single-grain bulk RE-Ba-Cu-O materials, which are synthesized using a top-seeded melt-growth (TSMG) process. Here, NdBa 2 Cu3Oy crystals are used as seeds for texturing or grain alignment. Critical currents of bulk RE-Ba-Cu-O can be enhanced by dispersing non-superconducting particles such as RE 2 BaCuO5. Encapsulation of bulk RE-Ba-Cu-O and resin impregnation are effective in improving mechanical properties. Resin impregnation is also effective in improving the corrosion resistance. Engineering applications of bulk RE-BaCu-O are categorized into three groups: magnetic levitation, high field magnet and conductors. For magnetic levitation applications, people have been developing flywheel energy storage systems based on non-contact frictionless superconducting bearings. For high field applications, bulk superconductors are used as magnetic sources for superconducting motors and magnetically induced drug delivery systems. Current leads made of bulk superconductors are commonly used as a power supply for cryogen-free superconducting magnets.
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研究論文
  • 宮永 貴文, 土井 俊哉, 稲田 満, 大原 春樹, 平田 大輔, 白樂 善則 , 窪田 秀一, 嶋 邦弘, 鹿島 直二, 長屋 重夫
    47 巻 (2012) 12 号 p. 667-673
    公開日: 2013/01/31
    ジャーナル フリー
    The authors tried to install CeO 2/YSZ/CeO2 buffer layers, where the thicknesses of the CeO 2 (seed and cap layers) and YSZ were 80, 40 and 260 nm, for a 1 μm-thick YBCO (YBa 2 Cu3 O7)-coated conductor using Ni-electroplated {100}<001> textured Cu/SUS316 laminated tape. We found that oxygen from the atmosphere permeated through the buffer layers to the Cu tape surface during deposition of the 1 μm-thick YBCO layer, and that the diffused oxygen reacted with the Cu on the Cu tape surface. This resulted in the generation of a thick Cu-oxide layer between the CeO2 seed layer and the Cu tape, and thereby caused delamination of the buffer layers and/or YBCO layers. To prevent delamination, the deposition time was shortened. The Jc of the 1 μm-thick YBCO film prepared on the CeO 2 /YSZ/CeO 2 -buffered Ni-electroplated {100}<001> textured Cu/SUS316 laminated tape reached 1.5 MA/cm2 at 77 K in the self magnetic field.
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  • 柁川 一弘, 久家 広嗣, 井上 拓郎, 渡辺 和樹, 内田 侑史, 中村 武恒, 小林 弘明, 本郷 素行, 小島 孝之, 田口 秀之, ...
    47 巻 (2012) 12 号 p. 674-679
    公開日: 2013/01/31
    ジャーナル フリー
    An electric pump composed of an MgB2 motor is combined with superconducting level sensors using thin CuNisheathed MgB2 wires to transfer liquid hydrogen. An impeller is attached to the lower end of a rotating shaft on the MgB2 motor and covered with an outer casing to form a centrifugal pump. Then, the MgB2 motor and impeller are placed vertically inside a cryostat with an infill of liquid hydrogen. A glass Dewar vessel is prepared to receive the liquid hydrogen transferred from the cryostat containing the MgB2 motor. The MgB2 sensors are used not only to detect the level of liquid hydrogen but also to control the electric pump on the basis of their pre-estimated calibration curves. By using the assembled pump system, the liquid hydrogen is successfully transferred from the cryostat to the glass Dewar vessel via a transfer tube. (Translation of the article originally published in Cryogenics 52 (2012) 615-619)
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