著者
神原 陽一
出版者
公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.52, no.6, pp.383-388, 2017-11-20 (Released:2017-12-08)
参考文献数
83
被引用文献数
1

After obtaining my doctorate in engineering from Keio University, I spent five years as a researcher at the Tokyo Institute of Technology, Suzukakedai Campus in Yokohama. During that time, I made the first report on a material system called iron-based high-temperature superconductors (Fe-SCs). Research on Fe-SCs is still hot topic in condensed matter physics. Now, I am continuing my research mainly on the fabrication of superconducting wire using Fe-SCs, while being distracted by some traditional affairs as a member of the faculty. Research on Fe-SCs has encouraged young researchers towards the further discovery of novel layered superconductors. This article was prepared by updating the content of “A Private Story, Discovery of Iron-based High Tc Superconductors” previously published in the membership journal of the Physical Society of Japan (Nihon Butsuri Gakkaishi).
著者
山本 純也
出版者
公益社団法人 低温工学・超電導学会
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.11, no.5, pp.222-228, 1976-11-10 (Released:2010-02-26)
参考文献数
4

This article describes methods of measuring liquid helium quantity, preparing a transfer tube, experimental set up of a cryostat, precooling, and transfering liquid helium, The properties of liquid helium are also simply explained for beginners. Precooling by liquid nitrogen is strongly recommended for decreasing liquid helium consumption.
著者
田中 宗 棚橋 耕太郎 本橋 智光 高柳 慎一
出版者
公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.53, no.5, pp.287-294, 2018-09-20 (Released:2018-10-27)
参考文献数
34

Quantum annealing (QA) is a promising calculation method for obtaining a better solution to combinatorial optimization problems. QA is a natural computation technique proposed in the context of statistical physics in 1998. In 2011, the world's first commercial machine realizing QA experimentally was released. After that, the development of hardware and software has been exhaustive, and the studies on application search have been done using commercial QA machines. In this paper, we first explain the basics of QA without assuming the knowledge of statistical physics and quantum physics. We also show a couple of examples of application studies on QA. In addition, existing problems and overcoming other methods are explained.
著者
富岡 章 能瀬 眞一 八木 裕治郎
出版者
CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.41, no.1, pp.28-35, 2006

We have developed the production technology for HTS magnets used in power transformers. Two subjects were mainly studied (i.e., high-voltage technologies and large current and low AC loss technologies) to establish the production method for a 66 kV / 6.9 kV 10 MVA-class HTS power transformer. In order to verify the validity of the elemental technologies, a single-phase 66 kV / 6.9 kV 2 MVA-class model HTS transformer was manufactured and tested. The test results indicate that the elemental technologies established can be used for the development of a 66 kV / 6.9 kV 10 MVA-class HTS power transformer.
著者
中島 良 佐藤 和雄 甲斐 美香 小林 良雄
出版者
公益社団法人 低温工学・超電導学会
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.27, no.2, pp.152-157, 1992-04-25 (Released:2010-02-26)
参考文献数
10

Resistance vs. temperature relations of 200 carbon resistors (Allen Bradley 100Ω, 1/8W), widely used for cryogenic temperature measurements, were investigated in the range between liquid helium temperature and 20K. Obtained data are statistically evaluated, and it is apparently shown that the difference of the carbon resistor's lot affects the resistance value at the cryogenic temperatures. Four empirical formulas for the resistance vs. temperature relation proposed by other researchers are evaluated. According to this result, the equation, logR+K/logR=A+B/T, proposed by Clement et al. has most precise fitting below 10K. The authors propose a new empirical equation by applying Clement's equation. It is found that the three undecided coefficients, A, B and K of the equation can be calculated from the resistance at 4.2K alone, thus enabling one-point calibration at liquid helium temperature. Resistance changes caused by ten times temperature cyclings from room temperature to liquid helium temperature are also measured. These are within -0.05-+0.02K, though measurments are slightly diverged by temperature cyclings.
著者
吉田 清
出版者
公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.44, no.8, pp.346-352, 2009 (Released:2009-10-15)
参考文献数
17
被引用文献数
1 1

The upgrading of the JT-60U to the JT-60SA has started in a joint effort by the Japanese government (JA) and European commission (EU) under the framework of the Broader Approach (BA) Agreement. The superconducting magnet system for the JT-60SA consists of 18 toroidal field (TF) coils, a central solenoid (CS) with four modules, and six equilibrium field (EF) coils. The TF case encloses the winding pack and is the main structural component of the magnet system. The CS consists of independent winding pack modules, which are hung from the top of the TF coils through its pre-load structure. The six EF coils are attached to the TF coil case through supports with flexible plates that allow radial displacement. The CS modules operate at high field and use a Nb3Sn superconductor. The TF coils and EF coils use NbTi superconductors. This paper describes the technical requirements, operational interface and detailed manufacturing design outline of the superconducting magnet system for the JT-60SA.
著者
宇佐美 貴史 吉田 隆 一野 祐亮 菅野 未知央 町屋 修太郎 衣斐 顕 和泉 輝郎
出版者
公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.51, no.6, pp.259-264, 2016

<p>The strain effect of REBa<sub>2</sub>Cu<sub>3</sub>O<i><sub>y</sub></i> (REBCO: RE = Y, Gd, Sm)-coated conductors (CCs) on critical current (<i>I</i><sub>c</sub>) is one of the most fundamental factors for superconducting coil applications. In this study, we aim to clarify the effect of artificial pinning center shapes on the strain effect in BHO-doped GdBCO CCs<sub>.</sub> To achieve this, we fabricated a Pure-GdBCO CC, a BHO nanorod-doped GdBCO CC and a multilayered-GdBCO (ML-GdBCO) CC, and carried out bending tests. As the result, the strain dependence of <i>I</i><sub>c</sub> for each CC showed an upward convex and the<i> </i>peak strain of the BHO-doped GdBCO CC shifts towards the compressive strain independent of the BHO shapes. In addition, the strain sensitivity of <i>I</i><sub>c</sub> in the GdBCO CCs including BHO becomes smaller. To clarify the difference between the strain sensitivity of <i>I</i><sub>c</sub> and the peak strain among the CCs, we evaluated the residual strain and the slopes of the internal lattice strains against the applied tensile strain (<i>&beta;</i>). From this measurement, the residual strains for the Pure-GdBCO CC and the ML-GdBCO CC were almost the same. In addition, there was no change in the <i>&beta;</i> value between the Pure-GdBCO and ML-GdBCO CCs. These results suggest that the changes in peak strain and strain sensitivity were not related to the internal lattice strain.</p>
著者
花田 卓爾
出版者
CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.15, no.2, pp.128-140, 1980-05-25 (Released:2010-02-26)

On September, 1978, Hydrogen Liquefaction Unit was established with a new plan to distribute customers by an industrial larger scale more than ever the way it had been applied. By this inovation caused in hydrogen distribution system, new chance was developed for the people who have not any knowladge and experience on the use of the liquid hydrogen.Accordingly, it is naturally requested to master the way of Liquid Hydrogen Safety Handring. This point will be guidance for people, operater and designer to easy handling the liquid hydrogen in the future.
著者
山本 明保 Jeremy WEISS Mark AINSLIE Anatolii POLYANSKII David LARBALESTIER Eric HELLSTROM
出版者
公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.52, no.6, pp.397-404, 2017-11-20 (Released:2017-12-08)
参考文献数
47

This article reviews the recent development of bulk trapped field magnet made with iron-based superconductor (IBSC). A trapped field of over 1 T at 5 K and 0.5 T at 20 K has been measured between a stack of magnetized cylinders of bulk polycrystalline Ba0.6K0.4Fe2As2 superconductors 10 mm in diameter. Magneto-optical imaging revealed a trapped field distribution corresponding to uniform macroscopic current loops circulating through the sample. A standard numerical modelling technique using the measured Jc(B, T) characteristics of a small specimen reproduced the experimentally measured trapped fields well, again indicating the homogeneous current loops in the polycrystalline bulk. Given the untextured polycrystalline nature of the cylinders and their large irreversibility field, it is expected that larger IBSC bulks could trap much higher field.
著者
松下 照男 船木 和夫
出版者
公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.39, no.1, pp.2-9, 2004 (Released:2007-02-16)
参考文献数
10

This article focuses on Poynting’s vector which is defined by a vector product of electric and magnetic fields and plays an important role in considering a flow of electromagnetic energy between power supplies and various types of electromagnetic devices in electrical, electronical and information networks. Poynting’s vector is introduced from a law of energy conservation and its surface integral on an arbitrary domain is equal to the electromagnetic power inside it. This relation can be applied to any system in which there is an interest in the energy flow. Validity of the speculation that Poynting’s vector directly gives the energy flow is examined in various cases. It is pointed out that Poynting’s vector is not equal to the energy flow in some cases. Also discussed is the condition under which the equality holds.
著者
小林 慎一 中島 隆芳 山崎 浩平 佐藤 謙一
出版者
公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.47, no.7, pp.422-429, 2012-07-25 (Released:2012-09-12)
参考文献数
27
被引用文献数
2 2

Since the discovery of bismuth-based high-temperature superconductors in 1988 in Japan, much work has been done to develop superconducting wires and their applications. Applications include cables, motors, transformers and fault current limiters used at 77.3 K, high field magnets and motors used at 20 K and super-high field magnets and current leads used at 4.2 K. Some applications are already commercial products. This paper introduces the wire fabrication methods, wire characteristics and application apparatus.
著者
大平 勝秀
出版者
公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.41, no.2, pp.61-72, 2006 (Released:2007-02-15)
参考文献数
29
被引用文献数
6 6

Since liquid hydrogen has a high specific impulse as fuel for rockets, its technology has been developed in connection with space technology programs. On the other hand, with the recent advance of technologies such as fuel-cell vehicles and stationary fuel-cell systems, liquid hydrogen is also expected to be used as an efficient means of transporting and storing hydrogen used as a source for clean energy. Slush hydrogen is a two-phase solid-liquid cryogenic fluid consisting of solid hydrogen particles in liquid hydrogen. Compared with liquid hydrogen, the density and cryogenic heat capacity of slush hydrogen with a solid fraction of 50% increase by 16% and 18%, respectively. Various applications of slush hydrogen are anticipated such as fuel for reusable space shuttles and fuel cells, and as a more efficient means of transporting and storing liquid hydrogen. This paper describes the applications and technology developments of liquid and slush hydrogen.
著者
中島 洋
出版者
CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.37, no.4, pp.148-156, 2002-04-25 (Released:2010-02-26)
参考文献数
11

The development of a superconducting Maglev system in Japan was started more than 30 years ago. Since 1997, the running tests have been successfully continued on the Yamanashi test line. A manned run in 1999 attained a speed of 552km/h, The Yamanashi test results proved a remarkable stability of the onboard superconducting magnet system, In these 30 years, we have encountered many difficult problems during this development. In this paper, the history of the Maglev development will be introduced with focus on these problems, especially in regard to the superconducting magnets and onboard refrigerators.
著者
三木 孝史 斉藤 一功 林 征治 梶川 弘 嶋田 雅生 小川 陸郎 川手 剛雄 池谷 大 木村 則幸 高畠 和男 西澤 節 杉浦 伸裕 鈴木 基文
出版者
CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.31, no.5, pp.258-266, 1996-05-25 (Released:2010-02-26)
参考文献数
14
被引用文献数
1 1

So far, the use of superconducting magnets has been limited to chemical analysis and medical inspection. To develop a new use, we have tried to apply common MRI devices as nondestructive sugar content detector of watermelon. To estimate the sugar content, a new technique using multiple regression analysis of two NMR relaxation times was developed. It was found that the coefficient of multiple regression at the center of the watermelon exceeded 0.9 and the standard error of prediction was around 0.5, and that the over-ripened part of flesh called ‘nieka’ in watermelon could be distinguished because its T2 was much longer than that of the oridinary part. An evaluation rate of sugar content could be below 6s per watermelon. It is concluded that multiple analysis of T1 and T2 on intact watermelon can be applied as a non-invasive, nondestructive indicator of sugar content.
著者
川島 健司 伊豫 彰 荻野 拓
出版者
公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.52, no.6, pp.389-396, 2017-11-20 (Released:2017-12-08)
参考文献数
46

We report discoveries and properties of new 112-type (Ca,Ln)FeAs2 (Ln = La ~ Gd) and 1144-type AeAFe4As4(Ae = Ca, Sr, Ba, Eu, A = K, Rb, Cs) Fe-based superconductor structures. (Ca,Ln)FeAs2 has a monoclinic system with a space group P21/m composed of two Ca(Pr) planes, Fe2As2 layers, and As2 zigzag chain layers. (Ca,Ln)FeAs2 shows superconductivity with a transition temperature (Tc) at 20 ~ 40 K. Although (Ca,Ln)FeAs2 has thick blocking layers, it has relatively high critical current density over 106 A/cm2 at 5 K (self-field). AeAFe4As4 has a tetragonal system with a space group, P4/mmm, Ae and A layers are inserted alternately between the Fe2As2 layers in the c-axis direction. AeAFe4As4 is a stoichiometric compound having Tc = 31 ~ 36 K, depending only on the combination of Ae and A. Both new superconductors are promising materials for application due to their characteristic properties.
著者
大塚 泰一郎
出版者
低温工学協会
雑誌
低温工学 (ISSN:03892441)
巻号頁・発行日
vol.35, no.12, pp.568-574, 2000-12-25
参考文献数
10