Author
Ko Yasukochi
Bio: Ko Yasukochi is an academic researcher from Nihon University. The author has contributed to research in topics: Electromagnetic coil & Superconductivity. The author has an hindex of 13, co-authored 43 publications receiving 558 citations.
Papers
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TL;DR: In this paper, the influence of oscillating magnetic fields on the dc transport current in a single core superconducting wire has been studied by observing the terminal voltage of the wire.
91 citations
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TL;DR: In this article, the influence of dc transport currents on alternating-field hysteresis loss was investigated for a single core superconducting wire, and the results were compared with calculations based on a slab model.
58 citations
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TL;DR: In this paper, magnetization measurements have been made on rare earth intermetallic compounds in Gd(Ag, Cd, In) and Gd (Cu, Ag, Au) systems to determine the magnetic order and its relationship to the number of conduction electrons.
Abstract: Rare earth intermetallic compounds in Gd(Ag, Cd, In) and Gd(Cu, Ag, Au) systems have been studied. Most of these compounds have the CsCl type of crystal structure. Magnetization measurements have been made on these compounds to determine the type of the magnetic order and its relationship to the number of conduction electrons. GdAg, GdAg 0.9 In 0.1 , GdAg 0.2 In 0.8 , GdAg 0.1 In 0.9 , and GdIn in the Gd(Ag, In) system and GdCu, GdAg, GdAg 0.7 Au 0.3 , and GdAg 0.5 Au 0.5 in the Gd(Cu, Ag, Au) system are antiferromagnetic at low temperatures. On the contrary, GdCd, GdAg 0.8 In 0.2 , GdAg 0.7 In 0.3 , GdAg 0.5 In 0.5 , and GdAg 0.3 In 0.7 are ferromagnetic at low temperatures. GdCd has a very high Curie temperature of 262°K. In the Gd(Cu, Ag, Au) system, the Neel temperature increases with the increase in the lattice constant. The remarkable difference in magnetic behavior between the Gd(Ag, Cd, In) system and the Gd(Cu, Ag, Au) system is considered to be associated with the fact that the number of conduct...
57 citations
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TL;DR: The properties of disilicides of Gd, Tb, Dy, Ho, and Er have been investigated at temperatures ranging from 4.2°K to room temperature as mentioned in this paper.
Abstract: Magnetic properties of disilicides of Gd, Tb, Dy, Ho, and Er have been investigated at temperatures ranging from 4.2°K to room temperature. All the disilicides except ErSi 2 have the orthorhombic ThSi 2 type of crystal structure and are shown to be antiferromagnetic. The Neel temperatures of GdSi 2 , TbSi 2 , DySi 2 and HoSi 2 are 27°K, 17°K, 17°K, and 18°K, respectively. The compound ErSi 2 has the hexagonal AlB 2 type of crystal structure and is paramagnetic at above 4.2°K. The paramagnetic Curie temperature of these compounds decreases with the number of f electrons of the rare earth ion.
47 citations
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TL;DR: Theoretical studies for transient field losses in multifilamentary composite conductors carrying a dc transport current are presented in this article, where the analysis of the total loss is split into separate calculations of the magnetization loss and the loss due to the dynamic resistance.
35 citations
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TL;DR: In this paper, the dielectric constant of undoped Ge was measured between 1.25 and 5.6 eV in the temperature range of 100 to 850 K. The dependence of the critical energies on temperature was obtained.
Abstract: Ellipsometric measurements of the dielectric constant of undoped Ge were performed between 1.25 and 5.6 eV in the temperature range of 100 to 850 K. The dependence of the ${E}_{1}$, ${E}_{1}+{\ensuremath{\Delta}}_{1}$, ${E}_{0}^{\ensuremath{'}}$, and ${E}_{2}$ critical energies on temperature was obtained. It can be represented either with Varshni's empirical formula or with an expression proportional to the Bose-Einstein statistical factor of an average phonon. Broadening parameters, amplitudes, and phase angles for the corresponding critical points were also obtained. A decrease of the excitonic interaction with increasing temperature was found. The results are discussed in the light of recent calculations of the effect of temperature on the band structure of Ge containing Debye-Waller and self-energy contributions.
614 citations
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TL;DR: The physical properties of many of the rare-earth intermetallic compounds have been discussed in terms of the role that the magnetic exchange and crystal field interactions play in determining these properties.
Abstract: The physical properties of many of the rare-earth intermetallic compounds have been collected together. They are discussed in terms of the role that the magnetic exchange and crystal field interactions play in determining these properties. It is pointed out that in this vast number of materials there is an ideal chance of establishing which of several second-order terms are effective in determining structural stability.
405 citations
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TL;DR: A review of the physical properties, composition and crystal structure of intermetallic compounds formed between rare-earth elements and non-magnetic metals, with emphasis on the magnetic properties is given in this article.
Abstract: A review is given of the physical properties, composition and crystal structure of intermetallic compounds formed between rare-earth elements and non-magnetic metals, with emphasis on the magnetic properties. Included are the properties of compounds in which the non-rare-earth component is a 4d or 5d transition element. Special consideration is given to the properties of pseudo-binary compounds. Results of magnetisation measurements, neutron diffraction and neutron scattering are discussed together with results derived from NMR, ESR and Mossbauer effect spectroscopy. An evaluation is given of the relevance of the experimental results with respect to different types of exchange interactions in this class of intermetallics. Special consideration is also given to the influence of crystal field effects on the magnetic properties and, furthermore, to the occurrence of intermediate valences in several of the compounds of Ce, Sm, Eu and Yb.
290 citations
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TL;DR: This paper presents a literature review of the methods for computing ac losses in HTS tapes, wires, and devices and provides an estimation of the losses occurring in a variety of power applications.
Abstract: Numerical modeling of superconductors is widely recognized as a powerful tool for interpreting experimental results, understanding physical mechanisms, and predicting the performance of high-temperature-superconductor (HTS) tapes, wires, and devices. This is particularly true for ac loss calculation since a sufficiently low ac loss value is imperative to make these materials attractive for commercialization. In recent years, a large variety of numerical models, which are based on different techniques and implementations, has been proposed by researchers around the world, with the purpose of being able to estimate ac losses in HTSs quickly and accurately. This paper presents a literature review of the methods for computing ac losses in HTS tapes, wires, and devices. Technical superconductors have a relatively complex geometry (filaments, which might be twisted or transposed, or layers) and consist of different materials. As a result, different loss contributions exist. In this paper, we describe the ways of computing such loss contributions, which include hysteresis losses, eddy-current losses, coupling losses, and losses in ferromagnetic materials. We also provide an estimation of the losses occurring in a variety of power applications.
290 citations
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TL;DR: In this article, the coupling losses for a range of shapes of superconducting wire and cable are calculated and general conclusions for the design of cables are drawn, and it is shown that the coupling loss can be expressed to a first approximation in terms of two parameters.
221 citations