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Ikeda, Yoichi*; Umemoto, Yoshihiko*; Matsumura, Daiju; Tsuji, Takuya; Hashimoto, Yuki*; Kitazawa, Takafumi*; Fujita, Masaki*
Materials Transactions, 64(9), p.2254 - 2260, 2023/09
Times Cited Count：0Soejima, Goro; Takiya, Hiroaki; Mizui, Hiroyuki; Fujita, Yoshihiko*; Akari, Eisaku*; Endo, Nobuyuki*; Kume, Kyo*
Heisei-27-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 18, P. 14, 2016/10
We have performed the preliminary re-conditioning test of the bituminization for radioactive wastes applying to the technical criteria by non-radioactive samples. As a result, we have confirmed the applicability to secure homogeneity that is a part of the technical criteria by evaluating sample properties.
Tezuka, Masashi; Koda, Yuya; Fujita, Yoshihiko*; Kume, Kyo*
Heisei-26-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 17, P. 78, 2015/10
In order to contribute to the segregated management in accordance with the level of contamination such as dismantling products, as a basis frame concrete specimens of the condenser, which has been laid in the turbine building of the "Fugen", pre-observation of such cracks status of surface on which was carried out to investigate the pollution status of internal specimen.
Tezuka, Masashi; Koda, Yuya; Fujita, Yoshihiko*; Endo, Nobuyuki*; Kume, Kyo*
Heisei-26-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 17, P. 78, 2015/10
In FUGEN, asphalt solidified body which was solidified the concentrated liquid waste is, some of them might also be present which do not meet the criteria (buried technical standards) according to the buried disposal of waste Therefore, these can not be buried disposal remain status quo. Therefore, it is assumed that that may not conform to the above criteria, "Asphalt solid material" is to conform to the reference to "re-processing", in addition to the desk study on specific measures, and also to preliminary tests I went.
Mizui, Hiroyuki; Fujita, Yoshihiko*; Kume, Kyo*
Heisei-25-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 16, P. 67, 2014/10
no abstracts in English
Matsunaga, Go; Takechi, Manabu; Aiba, Nobuyuki; Kurita, Genichi; Sakamoto, Yoshiteru; Koide, Yoshihiko; Isayama, Akihiko; Suzuki, Takahiro; Fujita, Takaaki; Oyama, Naoyuki; et al.
Plasma and Fusion Research (Internet), 4, p.051_1 - 051_7, 2009/11
no abstracts in English
Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Suzuki, Takahiro; Aiba, Nobuyuki; Takenaga, Hidenobu; Isayama, Akihiko; Shinohara, Koji; Yoshida, Maiko; Takechi, Manabu; et al.
Nuclear Fusion, 49(9), p.095017_1 - 095017_8, 2009/09
Times Cited Count：31 Percentile：74.06(Physics, Fluids & Plasmas)This paper reports the recent development of reversed shear plasmas with a high bootstrap current fraction towards reactor relevant regime, especially lower 
regime. By utilizing large volume configuration close to the conductive wall for wall stabilization, the beta limit of the reversed shear plasmas is significantly improved. As a result, high confinement reversed shear plasmas with high bootstrap current fraction exceeding no-wall beta limit are obtained in reactor relevant regime, where 
of 2.7, 
of 2.3 is achieved with reversed profile with 
of 2.3, and then HH
of 1.7, 
/
of 0.87 and 
of 0.9 are also obtained at of 5.3.
Ida, Katsumi*; Sakamoto, Yoshiteru; Yoshinuma, Mikiro*; Takenaga, Hidenobu; Nagaoka, Kenichi*; Hayashi, Nobuhiko; Oyama, Naoyuki; Osakabe, Masaki*; Yokoyama, Masayuki*; Funaba, Hisamichi*; et al.
Nuclear Fusion, 49(9), p.095024_1 - 095024_9, 2009/09
Times Cited Count：29 Percentile：72.01(Physics, Fluids & Plasmas)Dynamics of ion internal transport barrier (ITB) formation and impurity transport both in the Large Helical Device (LHD) heliotron and JT-60U tokamak are described. Significant differences between heliotron and tokamak plasmas are observed. The location of the ITB moves outward during the ITB formation regardless of the sign of magnetic shear in JT-60U and the ITB becomes more localized in the plasma with negative magnetic shear. In LHD, the low Te/Ti ratio (
1) of the target plasma for the high power heating is found to be necessary condition to achieve the ITB plasma and the ITB location tends to expand outward or inward depending on the condition of the target plasmas. Associated with the formation of ITB, the carbon density tends to be peaked due to inward convection in JT-60U, while the carbon density becomes hollow due to outward convection in LHD. The outward convection observed in LHD contradicts the prediction by neoclassical theory.
Urano, Hajime; Takenaga, Hidenobu; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Oyama, Naoyuki; Yoshida, Maiko; JT-60 Team
Nuclear Fusion, 48(8), p.085007_1 - 085007_9, 2008/08
Times Cited Count：9 Percentile：35.34(Physics, Fluids & Plasmas)Relation between heat transport in the plasma core and toroidal rotation profile was examined in conventional ELMy H-mode plasmas in JT-60U. Energy confinement improvement is observed with toroidal rotation which increases in co-direction with respect to the plasma current. Heat transport in the plasma core varies while sustaining self-similar temperature profile in the variation of toroidal rotation profiles. Large increase in heat conduction imposes the resilient profile of ion temperature, under which local effect of toroidal rotation profile on the scale length of ion temperature gradient is very weak. When the pedestal temperature was fixed between the cases of co and counter-NBI by adjusting the plasma density, the identical temperature profiles were obtained in spite of totally different toroidal rotation profiles.
Ida, Katsumi; Sakamoto, Yoshiteru; Takenaga, Hidenobu; Oyama, Naoyuki; Ito, Kimitaka*; Yoshinuma, Mikiro*; Inagaki, Shigeru*; Kobuchi, Takashi*; Isayama, Akihiko; Suzuki, Takahiro; et al.
Physical Review Letters, 101(5), p.055003_1 - 055003_4, 2008/08
Times Cited Count：33 Percentile：79.32(Physics, Multidisciplinary)A spontaneous transition phenomena between two meta-stable states of plasmas with internal transport barrier (ITB), that are characterized by different radial profiles of second derivative of ion temperature inside the ITB region where the ion temperature gradient is large, is observed in the steady-state phase of magnetic shear in the negative magnetic shear plasma in JT-60U tokamak. The curvature asymmetry factor evaluated from the radial profile of second derivative of ion temperature profiles changes from 0.08 (symmetric curvature ITB) to -0.43 (asymmetric curvature ITB) during transition phase.
Sakamoto, Yoshiteru; Takenaga, Hidenobu; Fujita, Takaaki; Ide, Shunsuke; Suzuki, Takahiro; Takechi, Manabu; Kamada, Yutaka; Oyama, Naoyuki; Isayama, Akihiko; Koide, Yoshihiko; et al.
Nuclear Fusion, 47(11), p.1506 - 1511, 2007/11
Times Cited Count：7 Percentile：25.84(Physics, Fluids & Plasmas)Controllability of plasmas with a large bootstrap current fraction () has been investigated in JT-60U. Dynamic change in current profile, especially , which was induced by change in pressure profile at the internal transport barrier (ITB) through rotation control, was observed, indicating the strong linkage among the profiles. Response of pressure and current profiles to off-axis neutral beam injection is investigated and found that the alignment of peaks of total current profile and beam driven current profile affects to location, and the change in toroidal rotation induces the movement of ITB location. The current profile in strong reversed shear plasma without current hole is largely varied in the core region by electron cyclotron current drive, while the ITB structure is not affected.
Shinohara, Koji; Sakurai, Shinji; Ishikawa, Masao; Tsuzuki, Kazuhiro*; Suzuki, Yutaka; Masaki, Kei; Naito, Osamu; Kurihara, Kenichi; Suzuki, Takahiro; Koide, Yoshihiko; et al.
Nuclear Fusion, 47(8), p.997 - 1004, 2007/08
Times Cited Count：40 Percentile：78.43(Physics, Fluids & Plasmas)Ferritic steel plates have been installed to improve the energetic ion confinement through reducing a toroidal magnetic field ripple. Aiming at cost-effective installation, orbit following calculations of energetic ions were performed for a design of ferritic installation on JT-60U by using the Fully three Dimensional magnetic field Orbit-Following Monte-Carlo (F3D OFMC) code. The installed ferritic steel adds the non-linear magnetic field on magnetic sensors for a plasma control and an equilibrium calculation. The code for a real-time control has been modified to take into account the magnetic field by ferritic steel. The plasma operation was successfully resumed and a real-time plasma control was successfully carried out after usual preparation processes. The heat load measurement indicates the improved confinement of energetic ions. These results are important for practical application of ferritic steel which is a leading candidate of a structural material on a demo reactor.
Shinohara, Koji; Sakurai, Shinji; Ishikawa, Masao; Tsuzuki, Kazuhiro*; Suzuki, Yutaka; Masaki, Kei; Naito, Osamu; Kurihara, Kenichi; Suzuki, Takahiro; Koide, Yoshihiko; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
Ferritic steel plates have been installed to improve the energetic ion confinement through reducing a toroidal magnetic field ripple. Aiming at cost-effective installation, orbit following calculations of energetic ions were performed for a design of ferritic installation on JT-60U by using the Fully three Dimensional magnetic field Orbit-Following Monte-Carlo (F3D OFMC) code. The installed ferritic steel adds the non-linear magnetic field on magnetic sensors for a plasma control and an equilibrium calculation. The code for a real-time control have been modified to take into account the magnetic field by ferritic steel. The plasma operation was successfully resumed and a real-time plasma control was successfully carried out after usual preparation processes. The heat load measurement indicates the improved confinement of energetic ions. These results are important for practical application of ferritic steel which is a leading candidate of a structural material on a demo reactor.
Takechi, Manabu; Matsunaga, Go; Ozeki, Takahisa; Aiba, Nobuyuki; Kurita, Genichi; Isayama, Akihiko; Koide, Yoshihiko; Sakamoto, Yoshiteru; Fujita, Takaaki; Kamada, Yutaka; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
This is the first experimental result which demonstrates the dependence of critical RWM onset of plasma rotation and beta on initial plasma rotation with the variation of the angular momentum input and without magnetic braking. In the JT-60U with newly ferretic wall installed, it is possible to produce high beta plasma tightly coupled with the wall (b/a=1.2) above 
. In near-zero plasma rotation, the RWM started to grow at = and with finite plasma rotation, the plasma pressure survives up to much higher 
level than that with small rotation. The observed critical beta onset 
and the RWM growth rate 
are discussed along with theoretical predictions using experimentally observed q-, pressure-, and rotation profiles. The critical rotation of RWM on JT-60U is less one-second times lower than previous report of other tokamaks.
Takechi, Manabu; Matsunaga, Go; Aiba, Nobuyuki; Fujita, Takaaki; Ozeki, Takahisa; Koide, Yoshihiko; Sakamoto, Yoshiteru; Kurita, Genichi; Isayama, Akihiko; Kamada, Yutaka; et al.
Physical Review Letters, 98(5), p.055002_1 - 055002_4, 2007/02
Times Cited Count：121 Percentile：94.54(Physics, Multidisciplinary)The plasma rotation necessary for stabilization of resistive wall modes (RWMs) is investigated by controlling the toroidal plasma rotation with external momentum input by injection of tangential neutral beams. The observed threshold is 0.3 % of the Alfv
n velocity and much smaller than the previous experimental results obtained with magnetic braking. This low critical rotation has a very weak dependence as the ideal wall limit is approached. These results indicate that for large plasmas such as in future fusion reactors with low rotation, the requirement of the additional feedback control system for stabilizing RWM is much reduced.
Ninomiya, Hiromasa; Akiba, Masato; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Inoue, Nobuyuki; et al.
Journal of the Korean Physical Society, 49, p.S428 - S432, 2006/12
To contribute DEMO and ITER, the design to modify the present JT-60U into superconducting coil machine, named National Centralized Tokamak (NCT), is being progressed under nationwide collaborations in Japan. Mission, design and strategy of this NCT program is summarized.
Sakamoto, Yoshiteru; Ide, Shunsuke; Yoshida, Maiko; Koide, Yoshihiko; Fujita, Takaaki; Takenaga, Hidenobu; Kamada, Yutaka
Plasma Physics and Controlled Fusion, 48(5A), p.A63 - A70, 2006/05
Times Cited Count：34 Percentile：73.6(Physics, Fluids & Plasmas)no abstracts in English
Hayashi, Nobuhiko; Takizuka, Tomonori; Sakamoto, Yoshiteru; Fujita, Takaaki; Kamada, Yutaka; Ide, Shunsuke; Koide, Yoshihiko
Plasma Physics and Controlled Fusion, 48(5A), p.A55 - A61, 2006/05
Times Cited Count：7 Percentile：24.66(Physics, Fluids & Plasmas)no abstracts in English
Kikuchi, Mitsuru; Tamai, Hiroshi; Matsukawa, Makoto; Fujita, Takaaki; Takase, Yuichi*; Sakurai, Shinji; Kizu, Kaname; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; et al.
Nuclear Fusion, 46(3), p.S29 - S38, 2006/03
Times Cited Count：13 Percentile：41.76(Physics, Fluids & Plasmas)The National Centralized Tokamak (NCT) facility program is a domestic research program for advanced tokamak research to succeed JT-60U incorporating Japanese university accomplishments. The mission of NCT is to establish high beta steady-state operation for DEMO and to contribute to ITER. The machine flexibility and mobility is pursued in aspect ratio and shape controllability, feedback control of resistive wall modes, wide current and pressure profile control capability for the demonstration of the high-b steady state.
Tsuchiya, Katsuhiko; Akiba, Masato; Azechi, Hiroshi*; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; et al.
Fusion Engineering and Design, 81(8-14), p.1599 - 1605, 2006/02
Times Cited Count：1 Percentile：9.98(Nuclear Science & Technology)no abstracts in English
