低温工学
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43 巻 , 11 号
選択された号の論文の6件中1~6を表示しています
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巻頭言
解説
  • 奥野 広樹
    43 巻 (2008) 11 号 p. 452-459
    公開日: 2008/12/27
    ジャーナル フリー
    The RIKEN Nishina Center began construction of the Radioactive Isotope Beam Factory (RIBF) in 1997, and succeeded in commissioning the beam of its accelerator complex at the end of 2006. The world’s first superconducting ring cyclotron (SRC) is the final booster in the RIBF accelerator complex. It is capable of accelerating all-element heavy ions to a speed of about 70% of the speed of light. Assembly of the superconducting sector magnets was completed in August 2005. The superconducting coils were successfully cooled down and excited for tests on many operational aspects: magnetic force, coil protection and quality of magnetic field, showing that they work as designed. After a series of tests the other components were installed and tested under stray fields from the sector magnets. Local magnetic shields were supplied for the components that could not work under the stray fields. After setting the beam vacuum and radio frequency, beam commissioning started. The first beam was extracted at the end of 2006, and the first uranium beam was extracted in March 2007.
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  • 杉本 英彦
    43 巻 (2008) 11 号 p. 460-467
    公開日: 2008/12/27
    ジャーナル フリー
    The research and development of superconductor motors using high-temperature superconductors is being carried out all over the world for the purpose of miniaturizing and efficiently upgrading motors. However, the practical applications of the motors have not been covered yet. In this explanation, the elements which constitute the high-temperature superconductor motor are described; namely, a high-temperature superconductor, cooling, and a synchronous motor .Specific examples of high-temperature superconductor motors for low-speed applications are also described.
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基礎講座
  • 松下 照男
    43 巻 (2008) 11 号 p. 468-475
    公開日: 2008/12/27
    ジャーナル フリー
    Flux pinning interaction originates from the variation in the energy of a flux line during its displacement across inhomogeneous regions called pinning centers such as normal precipitates or grain boundaries. The flux pinning mechanism is classified according to the dominant energy involved in the interaction. Normal precipitates and grain boundaries work as strong pinning centers through a condensation energy interaction. The field-induced pinning resulting from a weak superconducting region is also classified in the condensation energy interaction. Magnetic interaction and kinetic interaction are also introduced. The pinning mechanism of artificially introduced Nb into Nb-Ti is considered to be a kinetic energy interaction.
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研究論文
  • 方 美娜, 寺田 隆哉, 三島 史人, 秋山 庸子, 泉 佳伸, 西嶋 茂宏
    43 巻 (2008) 11 号 p. 476-481
    公開日: 2008/12/27
    ジャーナル フリー
    To separate oil contents from industrial and domestic wastewater with for the purpose of water purification and recyclying, magnetic separation of simulated emulsion wastewater was performed. Magnetic separation technology is roughly divided into magnetic seeding and magnetic separation. First, we confirmed the possibility of magnetically seeding emulsion using a flocculation method with polymer additives. For practical separation, we performed a separation experiment and particle trajectory simulation in a model system using a bulk superconducting magnet. From the results, we examined the basic conditions for highly effective magnetic separation of emulsions.
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  • 束野 豊, 土井 俊哉, 山下 裕生, 白樂 善則, 北口 仁, 高橋 健一郎, Harini SOSIATI, 波多 聰, 池田 賢一, ...
    43 巻 (2008) 11 号 p. 482-490
    公開日: 2008/12/27
    ジャーナル フリー
    In this paper, we examine the superconducting properties of MgB2+X thin films prepared with various compositions. MgB2+X thin films were prepared on polished silicon (100) single-crystal substrates using an electron beam evaporation technique without any post-annealing. The critical temperature of the MgB2+X thin film decreased in accordance with increasing B ratio in the B-rich composition region. However, ⊿Ms in the M-H curves of the B-rich MgB2 thin films were larger than that of the stoichiometric MgB2 thin film and the B-rich composition resulted in a longer c-axis length for the MgB2 crystal. These results suggest that Mg vacancies or B substitution on Mg sites in the MgB2+X crystals induced by the Mg-deficient composition act as effective pinning centers. Moreover, the chemical composition of the MgB2 superconductor strongly affected the stability of the microstructure in the MgB2 thin film. Therefore, we conclude that the slightly B-rich composition is preferable to the stoichiometric composition for the MgB2 superconductor.
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