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Suekuni, Koichiro*; Lee, C. H.*; Tanaka, Hiromi*; Nishibori, Eiji*; Nakamura, Atsushi*; Kasai, Hidetaka*; Mori, Hitoshi*; Usui, Hidetomo*; Ochi, Masayuki*; Hasegawa, Takumi*; et al.
Advanced Materials, 30(13), p.1706230_1 - 1706230_6, 2018/03
Times Cited Count：54 Percentile：89.14(Chemistry, Multidisciplinary)Thermoelectric materials for highly efficient devices must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. In this paper, we studied the crystal structure and phonon dynamics of tetrahedrites (Cu,Zn)
(Sb,As)
S
. The results revealed that the Cu atoms in a planar coordination are rattling, which effectively scatter phonons. These findings provide a new strategy for the development of highly efficient thermoelectric materials with planar coordination.
Okada, Michio*; Tsuda, Yasutaka*; Oka, Kohei*; Kojima, Kazuki*; Di
o, W. A.*; Yoshigoe, Akitaka; Kasai, Hideaki*
Scientific Reports (Internet), 6, p.31101_1 - 31101_8, 2016/08
Times Cited Count：28 Percentile：73.3(Multidisciplinary Sciences)We report results of our experimental and theoretical studies on the oxidation of Cu-Au alloy surfaces, viz., Cu
Au(111), CuAu(111), and AuCu(111), using hyperthermal O
molecular beam (HOMB). We observed strong Au segregation to the top layer of the corresponding clean (111) surfaces. This forms a protective layer that hinders further oxidation into the bulk. The higher the concentration of Au in the protective layer formed, the higher the protective efficacy. As a result, of the three Cu-Au surfaces studied, AuCu(111) is the most stable against dissociative adsorption of O, even with HOMB. We also found that this protective property breaks down for oxidations occurring at temperatures above 300 K.
Shibanuma, Kiyoshi; Arai, Takashi; Hasegawa, Koichi; Hoshi, Ryo; Kamiya, Koji; Kawashima, Hisato; Kubo, Hirotaka; Masaki, Kei; Saeki, Hisashi; Sakurai, Shinji; et al.
Fusion Engineering and Design, 88(6-8), p.705 - 710, 2013/10
Times Cited Count：10 Percentile：60.97(Nuclear Science & Technology)Takeda, Masayasu; Yamazaki, Dai; Soyama, Kazuhiko; Maruyama, Ryuji; Hayashida, Hirotoshi; Asaoka, Hidehito; Yamazaki, Tatsuya; Kubota, Masato; Aizawa, Kazuya; Arai, Masatoshi; et al.
Chinese Journal of Physics, 50(2), p.161 - 170, 2012/04
Asano, Shiro*; Okuyama, Toshihisa*; Onawa, Toshio*; Yanagi, Yutaka*; Ejiri, Mitsuru*; Kanahara, Toshio*; Ichihashi, Koji*; Kikuchi, Atsushi*; Mizumaki, Shoichi*; Masaki, Kei; et al.
Fusion Engineering and Design, 86(9-11), p.1816 - 1820, 2011/10
Times Cited Count：12 Percentile：66.68(Nuclear Science & Technology)The real vacuum vessel (VV) manufacturing of JT-60SA has started since Nov. 2009 at Toshiba. Prior to starting manufacturing, fundamental welding R&Ds had been performed by three stages. In the first stage, primary tests for screening welding method were performed. In the second stage, the trial welding for 1m-long straight and curved double shell samples were conducted. The dependences of welding quality and distortion on the welding conditions, such as arc voltage and current, setting accuracy, welding sequence, the shape of grooves, etc. were measured. In addition, welding condition with low heat input was explored. In the last stage, fabrication sequence was confirmed and established by the trial manufacturing of the 20
upper half mock-up. This poster presents the R&D results obtained in the first and second stages.
Morita, Takami*; Niwa, Kentaro*; Fujimoto, Ken*; Kasai, Hiromi*; Yamada, Haruya*; Nishiuchi, Ko*; Sakamoto, Tatsuya*; Godo, Waichiro*; Taino, Seiya*; Hayashi, Yoshihiro*; et al.
Science of the Total Environment, 408(16), p.3443 - 3447, 2010/06
Times Cited Count：13 Percentile：32.9(Environmental Sciences)Iodine-131 (
I) was detected in brown algae collected off the Japanese coast. The maximum measured specific activity of I in brown algae was 0.37
0.010 Bq/kg-wet. Cesium-137 (
Cs) was also detected in all brown algal samples used in this study. There was no correlation between specific activities of I and Cs in these seaweeds. Low specific activity and minimal variability of Cs in brown algae indicated that past nuclear weapon tests were the source of Cs. Although nuclear power facilities are known to be pollution sources of I, there was no relationship between the sites where I was detected and the locations of nuclear power facilities. Most of the sites where I was detected were near big cities with large populations. On the basis of the results, we suggest that the likely pollution source of I, detected in brown seaweeds, is not nuclear power facilities, but nuclear medicine procedures.
Hoshino, Katsumichi; Ido, Takeshi*; Nagashima, Yoshihiko*; Shinohara, Koji; Ogawa, Hiroaki; Kamiya, Kensaku; Kawashima, Hisato; Tsuzuki, Kazuhiro*; Kusama, Yoshinori; Oasa, Kazumi; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
We report on the potential/density fluctuations in the JFT-2M tokamak. We identified a geodesic acoustic mode (GAM) and its electric field structure. The GAM interacts with the background turbulence in consistent with a drift wave - zonal flow theory. The GAM modulates the turbulence, and the suppression depends on the direction and gradient of the flow velocity in consistent with a theory. During the H-mode, the GAM disappears presumably due to the suppression of the turbulence. We analysed the low frequency potential oscillation during the H-mode. A wavelet analysis showed a low frequency characteristic potential fluctuations (several handred kHz), which disappears in the L-mode and at the occurence of ELM. Observed poloidal flow is about 20 times as large as that of the GAM during the H-mode. If the potential has a spatial inhomogineity, there is a possibility that this low frequency fluctuation comes from the EXB flow or the zonal flow.
Tsuzuki, Kazuhiro; Kamiya, Kensaku; Shinohara, Koji; Bakhtiari, M.*; Ogawa, Hiroaki; Kurita, Genichi; Takechi, Manabu; Kasai, Satoshi; Sato, Masayasu; Kawashima, Hisato; et al.
Nuclear Fusion, 46(11), p.966 - 971, 2006/11
Times Cited Count：16 Percentile：48.19(Physics, Fluids & Plasmas)no abstracts in English
Kasai, Satoshi*; Kamiya, Kensaku; Shinohara, Koji; Kawashima, Hisato; Ogawa, Hiroaki; Uehara, Kazuya; Miura, Yukitoshi; Okano, Fuminori; Suzuki, Sadaaki; Hoshino, Katsumichi; et al.
Fusion Science and Technology, 49(2), p.225 - 240, 2006/02
Times Cited Count：3 Percentile：24.08(Nuclear Science & Technology)The diagnostic system of JFT-2M has consisted of about 30 individual diagnostic instruments,which were used to study the plasma production, control, equilibrium, stability, confinement, plasma heating by NBI and/or RF (LH, ICRF, ECH) and current drive by RF. In these instruments, the motional Stark effect (MSE) polarimeter, charge exchanged recombination spectroscopy (CXRS), heavy-ion beam probe (HIBP), time of flight (TOF) neutral particle analyzer, etc. have contributed to make clear the improved mechanism of confinement such as H-mode and High Recycling Steady (HRS) H-mode, and to search the operational region of these modes.The infrared TV camera system and lost ion probe have played a very important role to investigate the heat load onto the walls due to ripple loss particles and escaping ions from core plasma, respectively.
Tsuzuki, Kazuhiro*; Kimura, Haruyuki; Kusama, Yoshinori; Sato, Masayasu; Kawashima, Hisato; Kamiya, Kensaku; Shinohara, Koji; Ogawa, Hiroaki; Uehara, Kazuya; Kurita, Genichi; et al.
Fusion Science and Technology, 49(2), p.197 - 208, 2006/02
Times Cited Count：11 Percentile：60.11(Nuclear Science & Technology)no abstracts in English
Ogawa, Hiroaki; Yamauchi, Yuji*; Tsuzuki, Kazuhiro; Kawashima, Hisato; Sato, Masayasu; Shinohara, Koji; Kamiya, Kensaku; Kasai, Satoshi; Kusama, Yoshinori; Yamaguchi, Kaoru*; et al.
Journal of Nuclear Materials, 329-333(Part1), p.678 - 682, 2004/08
Times Cited Count：4 Percentile：29.18(Materials Science, Multidisciplinary)no abstracts in English
Tsuzuki, Kazuhiro; Shinohara, Koji; Kamiya, Kensaku; Kawashima, Hisato; Sato, Masayasu; Kurita, Genichi; Bakhtiari, M.; Ogawa, Hiroaki; Hoshino, Katsumichi; Kasai, Satoshi; et al.
Journal of Nuclear Materials, 329-333(1), p.721 - 725, 2004/08
Times Cited Count：7 Percentile：45.06(Materials Science, Multidisciplinary)no abstracts in English
Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Nakamura, Tatsuya; Kondo, Yasuhiro*; Chujo, Yoshiki*; Nanto, Hidehito*; Kojima, Takahiro*
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.274 - 279, 2004/08
Times Cited Count：30 Percentile：85.88(Instruments & Instrumentation)no abstracts in English
-ray discrimination characteristics of novel neutron scintillatorsKatagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Kojima, Takahiro*
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.317 - 320, 2004/08
Times Cited Count：15 Percentile：68.16(Instruments & Instrumentation)no abstracts in English
Kojima, Takahiro*; Katagiri, Masaki; Tsutsui, Noriaki*; Imai, Koji*; Matsubayashi, Masahito; Sakasai, Kaoru
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.325 - 328, 2004/08
Times Cited Count：40 Percentile：90.57(Instruments & Instrumentation)no abstracts in English
Kamiya, Kensaku; Bakhtiari, M.; Kasai, Satoshi; Kawashima, Hisato; Kusama, Yoshinori; Miura, Yukitoshi; Ogawa, Hiroaki; Oyama, Naoyuki; Sato, Masayasu; Shinohara, Koji; et al.
Plasma Physics and Controlled Fusion, 46(5A), p.A157 - A163, 2004/05
Times Cited Count：22 Percentile：56.33(Physics, Fluids & Plasmas)A new operating regime, High Recycling Steady (HRS) H-mode regime, has been discovered on JFT-2M, which is easily reproduced under the wall fueling from the boronized first wall. Accompanying the HRS H-mode transition, the coherent magnetic and floating potential fluctuations are seen on magnetic probes at vessel wall and Langmuir probe in SOL, respectively. These coherent fluctuations have a frequency of the order of 10-100 kHz with significant variation, which is recognized to be important to enhance the particle transport. The HRS can be seen even at 
3 with 
/
0.4 for the fixed delta
0.4 in the standard single-null divertor configuration. Recent experimental results from JFT-2M show that the plasma shape also seems to play an important role in determining the type of ELMs. The HRS regime can be extended up to delta0.75 and 2.6 in the double-null configuration, while lower delta boundary exists at delta0.3 with moderate 4 even at high recycling and/or density condition of /0.4.
Hoshino, Katsumichi; Nagashima, Yoshihiko*; Ido, Takeshi*; Tsuzuki, Kazuhiro; Kawashima, Hisato; Ogawa, Hiroaki; Bakhtiari, M.; Shinohara, Koji; Uehara, Kazuya; Oasa, Kazumi; et al.
Journal of Plasma and Fusion Research SERIES, Vol.6, p.345 - 348, 2004/00
no abstracts in English
Tsuzuki, Kazuhiro; Kimura, Haruyuki; Kawashima, Hisato; Sato, Masayasu; Kamiya, Kensaku; Shinohara, Koji; Ogawa, Hiroaki; Hoshino, Katsumichi; Bakhtiari, M.; Kasai, Satoshi; et al.
Nuclear Fusion, 43(10), p.1288 - 1293, 2003/10
Times Cited Count：39 Percentile：74(Physics, Fluids & Plasmas)no abstracts in English
Shinohara, Koji; Kawashima, Hisato; Tsuzuki, Kazuhiro; Urata, Kazuhiro*; Sato, Masayasu; Ogawa, Hiroaki; Kamiya, Kensaku; Sasao, Hajime; Kimura, Haruyuki; Kasai, Satoshi; et al.
Nuclear Fusion, 43(7), p.586 - 593, 2003/07
Times Cited Count：49 Percentile：80.09(Physics, Fluids & Plasmas)In JFT-2M, the ferritic steel was installed inside the vacuum vessel as the third step of tne Advanced Material Tokamak Experiment (AMTEX) programme. The magnetic field structure has become the complex ripple strucuture such as non-periodic ripple structure in the toroidal direction and high Fourier-number ripple because of the existence of the port and the limitation of the periodic installation. Under such a complex ripple structure, we have performed the experiment to understand its effect on fast ions. To actively change the ripple structure, we have installed the additional ferritic steel plates (FPs). We also have compared the experiment result with the newly updated OFMC code which does not need the toroidal 16-folded symmetry. The experiment results were almost consistent with the OFMC calcution with the complex magnetic field and the complex first wall.
Sugie, Tatsuo; Hatae, Takaki; Koide, Yoshihiko; Fujita, Takaaki; Kusama, Yoshinori; Nishitani, Takeo; Isayama, Akihiko; Sato, Masayasu; Shinohara, Koji; Asakura, Nobuyuki; et al.
Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.482 - 511, 2002/09
Times Cited Count：6 Percentile：3.03(Nuclear Science & Technology)The diagnostic system of JT-60U (JT-60upgrade) is composed of about 50 individual diagnostic devices. Recently, the detailed radial profile measurements of plasma parameters have been improved, so that the internal structure of plasmas has been explored. The understanding of plasma confinement has been enhanced by density and temperature fluctuation measurements using a mm-wave reflectometer and electron cyclotron emission measurements respectively. In addition, the real-time control experiments of electron density, neutron yield, radiated power and electron temperature gradient have been carried out successfully by corresponding diagnostic devices. These measurements and the real time control contribute to improving plasma performance. Diagnostic devices for next generation fusion devices such as a CO2 laser interferometer/polarimeter and a CO2 laser collective Thomson scattering system have been developed.
