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Aiba, Nobuyuki; Tokuda, Shinji; Ishizawa, Tomoko*
Journal of Plasma Physics, 72(6), p.1127 - 1131, 2006/12
Times Cited Count：1 Percentile：3.54(Physics, Fluids & Plasmas)We develop the method for the stability analysis of a ideal external magnetohydrodynamic (MHD) mode by solving the eigenvalue problem associated with the two-dimensional Newcomb equation, the inertia free linear ideal MHD equation. This eigenvalue problem can be expected to provide a powerful tool for not only a low-n external MHD mode but also a high-n mode, where n is a toroidal mode number. With this method, we analyze an effect of the aspect ratio on the stability of middle-n (1
n10) external MHD modes in tokamaks; this gets attention for the design research of a high performance tokamak. As the result of this work, we study that external MHD modes become stable as the aspect ratio decreases, and also find that the stability of middle-n external modes becomes important because an effect of a conducting wall is enhanced by reducing the aspect ratio.
Matsumoto, Taro; Naito, Hiroshi*; Tokuda, Shinji; Kishimoto, Yasuaki
Physics of Plasmas, 12(9), p.092505_1 - 092505_7, 2005/09
Times Cited Count：2 Percentile：6.85(Physics, Fluids & Plasmas)The behavior of the collisionless magnetohydrodynamics modes is investigated by the gyro-kinetic particle simulation in a cylindrical tokamak plasma in the parameter region where the effects of electron inertia and electron parallel compressibility are competitive for magnetic reconnection. Although the linear growth of the 
internal kink-tearing mode is dominated by the electron inertia, it is found that the growth rate can be nonlinearly accelerated due to the electron parallel compressibility proportional to the ion sound Larmor radius 
. It is also found that, as decreasing the electron skin depth 
, the maximum growth rate before the internal collapse saturates independently of the microscopic scales such as and . The acceleration of growth rate is also observed in the nonlinear phase of the 
double tearing mode.
Tamai, Hiroshi; Kurita, Genichi; Matsukawa, Makoto; Urata, Kazuhiro*; Sakurai, Shinji; Tsuchiya, Katsuhiko; Morioka, Atsuhiko; Miura, Yushi; Kizu, Kaname; Kamada, Yutaka; et al.
Plasma Science and Technology, 6(3), p.2281 - 2285, 2004/06
Times Cited Count：0 Percentile：0.02(Physics, Fluids & Plasmas)High performance steady-state operation for JT-60SC are evaluated by the TOPICS analysis. 
5 and bootstrap current fraction 86% is kept steady at I
=1.5 MA, B
=2 T by neutral beam power of 11 MW. The ERATO-J analysis shows that the external-kink mode with multiple toroidal mode numbers of n=1 and n=2 is stable at 
5.5 at the average ratio of conducting wall radius to plasma minor radius of about 1.2 with the wall stabilisation effect. Resistive wall modes, induced by a close location of the wall to plasma, is expected to be suppressed by the active feedback stabilisation with a set of non-axisymmetric field coils behind the stabilising plates. Further optimisation for the high- accessibility by the plasma shaping is performed with the TOSCA analysis. The plasma shaping factor defined as S=(I/aB)q
and strongly correlated to the plasma elongation and triangularity, is scanned from 4 to 6, which extends the availability of current and pressure profile control for the high performance plasma operation.
Matsumoto, Taro; Tokuda, Shinji; Kishimoto, Yasuaki; Naito, Hiroshi*
Physics of Plasmas, 10(1), p.195 - 203, 2003/01
Times Cited Count：5 Percentile：16.93(Physics, Fluids & Plasmas)Effects of density gradient on the collisionless m=1 internal kink mode in a cylindrical tokamak plasma are studied by the gyro-kinetic particle simulations. When the density gradient is not large enough to change the full reconnection process, the phenomena after the full reconnection, such as the secondary reconnection and the evolution of the safety factor profile, are changed considerably due to the self-generated radial electric field, i.e. the m=0 mode. The growing mechanism is explained by the difference of 
drift motion between ions and electrons, which is caused by the fast parallel motion of electron. Once the radial electric field is triggered by the symmetrical flow induced by the m=1 mode, the m=0 mode grows up to the same level as the m=1 mode, and drives an plasma rotation in the ion diamagnetic direction, which breaks the symmetrical plasma flow induced by the m=1 mode. The density and current distributions, and minimum safety factor after the full reconnection, are found to be affected by the asymmetrical flow driven by the m=1 and m=0 modes.
Wang, S.; Ozeki, Takahisa; Tobita, Kenji
Physical Review Letters, 88(10), p.105004_1 - 105004_4, 2002/03
Times Cited Count：130 Percentile：94.32(Physics, Multidisciplinary)A theoretical model has been established to show that energetic co-circulating ions can stabilize internal kink modes.And the theoretical model has been applied to interpret the recent experiments on sawtooth stabilization by energetic co-circulating ions.
Matsumoto, Taro; Tokuda, Shinji; Kishimoto, Yasuaki; Takizuka, Tomonori; Naito, Hiroshi*
Purazuma, Kaku Yugo Gakkai-Shi, 75(10), P. 1194, 1999/10
no abstracts in English
Ozeki, Takahisa; Ishii, Yasutomo; S.R.Hudson*; Tokuda, Shinji; Hamamatsu, Kiyotaka; Yamagiwa, Mitsuru; ; *; D.Monticello*; ; et al.
Fusion Energy 1998 (CD-ROM), 4 Pages, 1999/00
no abstracts in English
Matsumoto, Taro; Tokuda, Shinji; Kishimoto, Yasuaki; Takizuka, Tomonori; Naito, Hiroshi*
Journal of Plasma and Fusion Research SERIES, Vol.2, p.97 - 100, 1999/00
no abstracts in English
Ozeki, Takahisa
Purazuma, Kaku Yugo Gakkai-Shi, 74(9), p.998 - 1005, 1998/09
no abstracts in English
p plasmas and p collapse in JT-60UOzeki, Takahisa; Azumi, Masafumi; Kamada, Yutaka; Ishida, Shinichi; Neyatani, Yuzuru; Tokuda, Shinji
Nuclear Fusion, 35(7), p.861 - 871, 1995/00
Times Cited Count：28 Percentile：69.13(Physics, Fluids & Plasmas)no abstracts in English
Tokuda, Shinji; Ozeki, Takahisa
JAERI-Research 94-030, 13 Pages, 1994/11
JAERI-Research-94-030.pdf:0.62MB
no abstracts in English
Tokuda, Shinji; Ozeki, Takahisa
JAERI-Research 94-013, 16 Pages, 1994/09
JAERI-Research-94-013.pdf:0.66MB
no abstracts in English
Ozeki, Takahisa
JAERI-M 93-184, 214 Pages, 1993/10
no abstracts in English
plasmas in a tokamakOzeki, Takahisa; Azumi, Masafumi; Tokuda, Shinji; Ishida, Shinichi
Nuclear Fusion, 33(7), p.1025 - 1035, 1993/00
Times Cited Count：41 Percentile：76.05(Physics, Fluids & Plasmas)no abstracts in English
Yoshino, Ryuji; Kamada, Yutaka; Shimizu, Katsuhiro; Ozeki, Takahisa; Hirayama, Toshio; Sugie, Tatsuo; Nishitani, Takeo
Kaku Yugo Kenkyu, 65(SPECIAL ISSUE), p.163 - 183, 1991/03
no abstracts in English
Ozeki, Takahisa; Azumi, Masafumi; Kamada, Yutaka; Yoshino, Ryuji; Tokuda, Shinji; Tsunematsu, Toshihide; Nagashima, Keisuke; Yoshida, Hidetoshi;
Nuclear Fusion, 31(1), p.51 - 60, 1991/00
Times Cited Count：8 Percentile：41.47(Physics, Fluids & Plasmas)no abstracts in English
Ozeki, Takahisa; Azumi, Masafumi
Journal of the Physical Society of Japan, 59(12), p.4338 - 4345, 1990/12
Times Cited Count：0 Percentile：0.01(Physics, Multidisciplinary)no abstracts in English
Ozeki, Takahisa; Azumi, Masafumi; Ishida, Shinichi; Koide, Yoshihiko; Tokuda, Shinji
JAERI-M 90-180, 16 Pages, 1990/10
no abstracts in English
Ozeki, Takahisa; Azumi, Masafumi
JAERI-M 90-170, 23 Pages, 1990/10
no abstracts in English
Ozeki, Takahisa; Tokuda, Shinji; Tsunematsu, Toshihide; Ishida, Shinichi; Neyatani, Yuzuru; Itami, Kiyoshi; Azumi, Masafumi
JAERI-M 89-087, 24 Pages, 1989/07
no abstracts in English
