Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
La Haye, R. J.*; Prater, R.*; Buttery, R. J.*; Hayashi, Nobuhiko; Isayama, Akihiko; Maraschek, M. E.*; Urso, L.*; Zohm, H.*
Nuclear Fusion, 46(4), p.451 - 461, 2006/04
Times Cited Count：151 Percentile：97.55(Physics, Fluids & Plasmas)no abstracts in English
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
Ushigome, Masahiro*; Ide, Shunsuke; Ito, Satoshi*; Jotaki, Eriko*; Mitarai, Osamu*; Shiraiwa, Shunichi*; Suzuki, Takahiro; Takase, Yuichi*; Tanaka, Shigetoshi*; Fujita, Takaaki; et al.
Nuclear Fusion, 46(2), p.207 - 213, 2006/02
Times Cited Count：11 Percentile：37.01(Physics, Fluids & Plasmas)This papaer studies on tokamak plasma start-up completely without central solenoid (CS). On the JT-60 tokamak it is demonstrated that a completely CS-less Ip start-up to 100 kA was achieved even without any null-point by Electron cyclotron range of frequencies (ECRF) and outer PF coil current swing only. Necessary conditions (the EC power, the toroidal field etc.) were clarified. Moreover, it was succeded to maintain Ip = 260kA for 1 sec without CS by NB only. In addition Ip ramp-up by EC and NB only (without LHCD) from 215 to 310kA was achieved. In a high confinement reversed shear discharge, a result suggesting bootstrap over drive was obtained.
Isayama, Akihiko; JT-60 Team
Plasma Science and Technology, 8(1), p.36 - 40, 2006/01
Times Cited Count：4 Percentile：14.66(Physics, Fluids & Plasmas)no abstracts in English
Takatsu, Hideyuki; Konishi, Satoshi*
Purazuma, Kaku Yugo Gakkai-Shi, 81(11), p.837 - 902, 2005/11
Technology research and development issues, other than Breeding Blankets and Structural Materials, nesessary to be developed toward a fusion DEMO plant are introduced. Taking five critical technologies (Divertor, Superconducting Magnets, Tritium System, Heating and Current Drive system and Remote Maintenance System), target specifications and current status of technology research and development are outlined.
Fujita, Takaaki; Suzuki, Takahiro; Oikawa, Toshihiro; Isayama, Akihiko; Hatae, Takaki; Naito, Osamu; Sakamoto, Yoshiteru; Hayashi, Nobuhiko; Hamamatsu, Kiyotaka; Ide, Shunsuke; et al.
Physical Review Letters, 95(7), p.075001_1 - 075001_4, 2005/08
Times Cited Count：14 Percentile：60.97(Physics, Multidisciplinary)We found that no current can be driven in a central region of high-temperature, magnetically-confined, axi-symmetric torus plasma once the central current density becomes nearly zero ("current hole"), in spite of high electric conductivity. The current clamp was observed against current drive by a toroidal electric field and a radio-frequency wave in experiments on the JT-60U tokamak. This is a new, stiff, self-organized structure of magnetic field in an axi-symmetric torus plasma.
Okano, Kunihiko*; Suzuki, Takahiro; Umeda, Naotaka; Hiwatari, Ryoji*; Masaki, Kei; Tobita, Kenji; Fujita, Takaaki
Purazuma, Kaku Yugo Gakkai-Shi, 81(8), p.579 - 580, 2005/08
In a toroidal system, circulating fast ions generated by neutral beam injection affect the beam stopping cross-section of the neutral beam itself. This effect is called "beam particle self-interaction (BPSI)". In a recent experiment in JT-60U with 350 keV H
beam, an indication of this BPSI effect has been found for the first time. In a low density discharge at about 1
10
m
, the beam shine-through decreased by about 35% within several hundred msec after beam injection. This result is consistent with a prediction by the BPSI theory.
Sakamoto, Yoshiteru; Fujita, Takaaki; Ide, Shunsuke; Isayama, Akihiko; Takechi, Manabu; Suzuki, Takahiro; Takenaga, Hidenobu; Oyama, Naoyuki; Kamada, Yutaka; JT-60 Team
Nuclear Fusion, 45(7), p.574 - 580, 2005/07
Times Cited Count：41 Percentile：76.9(Physics, Fluids & Plasmas)This paper reports results on the progress in stationary discharges with a large bootstrap current fraction in JT-60U towards steady-state tokamak operation. In weak shear plasma regime, high-_p ELMy H-mode discharges have been optimized under nearly full non-inductive current drive by the large bootstrap current fraction (fBS
50%) and the beam driven current fraction (fBD
40%), which was sustained for 2.3s with stationary condition. The high confinement enhancement factor H892.3 (HH98y21.0) was also sustained under the condition of TeTi. In reversed shear plasma regime, the large bootstrap current fraction (fBS75%) has been sustained for 7.4 s under nearly full non-inductive current drive condition. The high confinement enhancement factor H893.0 (HH98y21.7) was also sustained, and the profiles of current and pressure approached the stationary condition. The large bootstrap current and the off-axis beam driven current sustained this reversed q-profile. This duration was limited only by the duration of the neutral beam injection.
Nagasaki, Kazunobu*; Isayama, Akihiko; Hayashi, Nobuhiko; Ozeki, Takahisa; Takechi, Manabu; Oyama, Naoyuki; Ide, Shunsuke; Yamamoto, Satoshi*; JT-60 Team
Proceedings of 20th IAEA Fusion Energy Conference (FEC 2004) (CD-ROM), 8 Pages, 2004/11
no abstracts in English
discharges and real-time control of current profile in JT-60USuzuki, Takahiro; Isayama, Akihiko; Sakamoto, Yoshiteru; Ide, Shunsuke; Fujita, Takaaki; Takenaga, Hidenobu; Luce, T. C.*; Wade, M. R.*; Oikawa, Toshihiro; Naito, Osamu; et al.
Proceedings of 20th IAEA Fusion Energy Conference (FEC 2004) (CD-ROM), 8 Pages, 2004/11
no abstracts in English
Takahashi, Koji
JAERI-Research 2004-011, 125 Pages, 2004/09
JAERI-Research-2004-011.pdf:9.32MB
no abstracts in English
Tobita, Kenji; Ozeki, Takahisa; Nakamura, Yukiharu
Plasma Physics and Controlled Fusion, 46(7), p.S95 - S105, 2004/07
Times Cited Count：10 Percentile：32.04(Physics, Fluids & Plasmas)no abstracts in English
Matsukawa, Makoto; JT-60SC Design Team
IEEE Transactions on Applied Superconductivity, 14(2), p.1399 - 1404, 2004/06
Times Cited Count：4 Percentile：28.63(Engineering, Electrical & Electronic)no abstracts in English
Suzuki, Takahiro; Ide, Shunsuke; Hamamatsu, Kiyotaka; Petty, C. C.*; Lao, L. L.*; Isayama, Akihiko; Fujita, Takaaki; Ikeda, Yoshitaka; Seki, Masami; Moriyama, Shinichi; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 80(6), p.511 - 515, 2004/06
no abstracts in English
Suzuki, Takahiro; Ide, Shunsuke; Hamamatsu, Kiyotaka; Isayama, Akihiko; Fujita, Takaaki; Petty, C. C.*; Ikeda, Yoshitaka; Kajiwara, Ken*; Naito, Osamu; Seki, Masami; et al.
Nuclear Fusion, 44(7), p.699 - 708, 2004/05
Times Cited Count：31 Percentile：69.25(Physics, Fluids & Plasmas)no abstracts in English
Suzuki, Takahiro; Oikawa, Toshihiro; Isayama, Akihiko; Fujita, Takaaki
Purazuma, Kaku Yugo Gakkai-Shi, 80(5), p.362 - 363, 2004/05
An analytical method to evaluate spatio-temporal change in current density profile directly from the motional Stark effect (MSE) diagnostic is applied to a discharge, where a neo-classical tearing mode (NTM) appeared and was stabilized by electron cyclotron current drive (ECCD). The analysis clearly shows spatially localized decrease in current density at the magnetic island location, implying decrease in bootstrap current due to flattening of pressure profile within the island. When the NTM is stabilized after the start of the ECCD application, increase in current density at the island location is observed.
Oikawa, Toshihiro
JAERI-Research 2003-028, 134 Pages, 2004/01
JAERI-Research-2003-028.pdf:7.73MB
The negative ion based neutral beam (N-NB) driven current density was determined over a wide range of electron temperatures. Theoretical prediction of the NB current drive increasing with beam energy and electron temperature was validated. A record value of NB current drive efficiency was achieved simultaneously with high confinement and high beta at a plasma current of 1.5 MA under a full current drive condition. The experimental validation of NB current drive theory gives greater confidence in predicting the NB current drive in future reactors. However, it was also found that MHD instabilities caused a degradation of NB current drive. A beam-driven instability expelled N-NB fast ions carrying non-inductive current from the central region. The lost N-NB driven current was estimated to be 7 % of the total N-NB driven current. For the neoclassical tearing mode (NTM), comparisons of the measurements with transport code calculations revealed that the loss of fast ions increases with the NTM activity and that fast ions at higher energies suffer larger transport than at lower energies.
Shiraiwa, Shunichi*; Ide, Shunsuke; Ito, Satoshi*; Mitarai, Osamu*; Naito, Osamu; Ozeki, Takahisa; Sakamoto, Yoshiteru; Suzuki, Takahiro; Takase, Yuichi*; Tanaka, Shigetoshi*; et al.
Physical Review Letters, 92(3), p.035001_1 - 035001_4, 2004/01
Times Cited Count：46 Percentile：82.94(Physics, Multidisciplinary)no abstracts in English
Nagasaki, Kazunobu*; Isayama, Akihiko; Ide, Shunsuke; JT-60 Team
Nuclear Fusion, 43(10), p.L7 - L10, 2003/10
Times Cited Count：48 Percentile：79.65(Physics, Fluids & Plasmas)no abstracts in English
Takase, Yuichi*; JT-60 Team
AIP Conference Proceedings 694, p.235 - 242, 2003/05
A central electron temperature of 23 keV was obtained by EC wave injection. A highly localized current density profile was obtained by central ECCD, indicating an upper limit on the diffusion coefficient for resonant electrons of 
. The experimentally obtained current drive figure of merit was lower than theoretical prediction, possibly because of the negative loop voltage induced by overdrive. A comparison of HFS and LFS off-axis ECCD confirmed the theoretically expected trapped particle effect on the current drive efficiency. Offaxis LHCD was used to broaden the qmin radius and the ITB foot radius. N-NBCD was used to shrink the current hole radius. An integrated scenario consisting of (1) a novel plasma start-up method using RF plasma production and induction by vertical field and shaping coils, (2) a noninductive ramp-up stage, and (3) a transition to a high-density, bootstrap-dominated, highconfinement plasma, without the use of the OH solenoid, has been demonstrated. The plasma created by this technique had both internal and edge transport barriers, with 
(
), 
, 
and 
at 
MA and 
.
