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Kawamura, Kazuhiro; Koide, Manabu*; Matsushita, Kazumasa*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 13(1), p.27 - 33, 2014/03
The temperature dependence of viscosity below and above the glass transition temperature (Tg) of simulated high-level radioactive waste (HLW) glass was measured by the fibre bending method and the parallel plate method. The ratio of activation energy for viscous flow below Tg to that above Tg was found to be 0.1, which is significantly smaller than the generally accepted value of 0.5. The long-term crystallization time of HLW glass below Tg was estimated from measured crystallization and viscosity data. A formula of the long-term crystallization time was evaluated with the assistance of a TTT diagram. The HLW glass was evaluated to have a sufficiently long-term stability, even if it is exposed to a maximum temperature of 150 
C during the disposal period.
Matsumoto, Yoshihiro; Entani, Shiro; Koide, Akihiro*; Otomo, Manabu; Avramov, P.; Naramoto, Hiroshi*; Amemiya, Kenta*; Fujikawa, Takashi*; Sakai, Seiji
Journal of Materials Chemistry C, 1(35), p.5533 - 5537, 2013/09
Times Cited Count：32 Percentile：76.83(Materials Science, Multidisciplinary)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：33 Percentile：73.96(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.
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：25.77(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.
Oyama, Naoyuki; Isayama, Akihiko; Suzuki, Takahiro; Koide, Yoshihiko; Takenaga, Hidenobu; Ide, Shunsuke; Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Takechi, Manabu; et al.
Nuclear Fusion, 47(7), p.689 - 697, 2007/07
Times Cited Count：15 Percentile：47.3(Physics, Fluids & Plasmas)After the installation of FSTs in JT-60U, ripple induced fast ion losses have been reduced by 1/2
1/3. The increase in the absorbed power at the same injection power can reduce the required number of NB units to sustain a given 
. The smaller recycling level and edge density, which is suitable condition to get higher edge temperature, can be kept longer. The higher edge temperature is essential in keeping the peaked pressure/temperature profile. In addition to this, smaller fast ion losses reduce the effective torque for ctr-rotation and increase in better flexibility of torque input. Then, better quality of 
-ITB was obtained in the plasmas with co-rotation. By making use of these advantages to sustain an ITB, the performance of long-pulse ELMy H-mode plasmas was improved in terms of sustained duration time for both high and high thermal confinement enhancement factor (
). High 
2.3 together with 1 was sustained for 23.1s (
, where 
is the current diffusion time.), which also provide high 
. These long-pulse plasmas are possible candidates for ITER hybrid operation scenario.
Oyama, Naoyuki; Kamada, Yutaka; Isayama, Akihiko; Urano, Hajime; Koide, Yoshihiko; Sakamoto, Yoshiteru; Takechi, Manabu; Asakura, Nobuyuki; JT-60 Team
Plasma Physics and Controlled Fusion, 49(3), p.249 - 259, 2007/03
Times Cited Count：32 Percentile：72.05(Physics, Fluids & Plasmas)no abstracts in English
Oyama, Naoyuki; Isayama, Akihiko; Suzuki, Takahiro; Koide, Yoshihiko; Takenaga, Hidenobu; Ide, Shunsuke; Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Takechi, Manabu; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
After installation of ferritic steel tiles (FSTs) which reduced fast ion losses due to toroidal field ripple, the performance of long-pulse ELMy H-mode plasmas was improved in terms of sustained duration time for both high normalized beta (
) and high thermal confinement enhancement factor (
). High 2.3 together with 1 was sustained for 23.1s (12
) 
, which also provide high 
, which is higher than ITER reference scenario. These long-pulse plasmas are possible candidates for ITER hybrid operation scenario.
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：94.5(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.
Matsunaga, Go; Takechi, Manabu; Kurita, Genichi; Sakamoto, Yoshiteru; Koide, Yoshihiko; Isayama, Akihiko; Suzuki, Takahiro; Fujita, Takaaki; Aiba, Nobuyuki; Ozeki, Takahisa; et al.
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
Oyama, Naoyuki; Urano, Hajime; Yoshida, Maiko; Takenaga, Hidenobu; Shinohara, Koji; Sakurai, Shinji; Masaki, Kei; Kamiya, Kensaku; Isayama, Akihiko; Suzuki, Takahiro; et al.
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
Shinohara, Koji; Sakurai, Shinji; Ishikawa, Masao; Koide, Yoshihiko; Nakano, Tomohide; Tsuzuki, Kazuhiro; Oyama, Naoyuki; Yoshida, Maiko; Urano, Hajime; Suzuki, Yutaka; et al.
no journal, ,
no abstracts in English
Matsunaga, Go; Takechi, Manabu; Isayama, Akihiko; Sakamoto, Yoshiteru; Koide, Yoshihiko; Yoshida, Maiko; Suzuki, Takahiro; Fujita, Takaaki; Ozeki, Takahisa; Kurita, Genichi
no journal, ,
no abstracts in English
Matsunaga, Go; Takechi, Manabu; Sakamoto, Yoshiteru; Koide, Yoshihiko; Suzuki, Takahiro; Fujita, Takaaki; Aiba, Nobuyuki; Kurita, Genichi; Ozeki, Takahisa; JT-60 Team
no journal, ,
no abstracts in English
Oyama, Naoyuki; Isayama, Akihiko; Suzuki, Takahiro; Koide, Yoshihiko; Takenaga, Hidenobu; Ide, Shunsuke; Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Takechi, Manabu; et al.
no journal, ,
no abstracts in English
Takechi, Manabu; Matsunaga, Go; Ozeki, Takahisa; Aiba, Nobuyuki; Kurita, Genichi; Isayama, Akihiko; Koide, Yoshihiko; Sakamoto, Yoshiteru; Fujita, Takaaki; Kamada, Yutaka; et al.
no journal, ,
no abstracts in English
Urasaki, Hisashi*; Takechi, Manabu; Matsunaga, Go; Isayama, Akihiko; Koide, Yoshihiko; Sakamoto, Yoshiteru; Fujita, Takaaki; Tsutsui, Hiroaki*; Iio, Shunji*; Shimada, Ryuichi*; et al.
no journal, ,
no abstracts in English
Matsunaga, Go; Takechi, Manabu; Aiba, Nobuyuki; Kurita, Genichi; Sakamoto, Yoshiteru; Koide, Yoshihiko; Isayama, Akihiko; Suzuki, Takahiro; Fujita, Takaaki; Ozeki, Takahisa; et al.
no journal, ,
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.
no journal, ,
This paper reports the development of reversed magnetic shear plasmas with a large bootstrap current fraction towards reactor relevant regime, especially lower q95 regime. By utilizing large volume configuration close to the conductive wall for wall stabilization, the beta limit of reversed shear plasmas is significantly improved. As a result, high confinement reversed shear plasmas with large bootstrap current fraction exceeding no-wall beta limit are obtained in reactor relevant regime, where betaN=2.7, betap=2.3 is achieved with reversed q profile with qmin=2.3, and then HH98y2=1.7, ne/nGW=0.87 and fBS=0.9 are also obtained at q95=5.3.
