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Journal Articles

Nonlinear acceleration of the electron inertia-dominated magnetohydrodynamic modes due to electron parallel compressibility

Matsumoto, Taro; Naito, Hiroshi*; Tokuda, Shinji; Kishimoto, Yasuaki

Physics of Plasmas, 12(9), p.092505_1 - 092505_7, 2005/09

https://doi.org/10.1063/1.2042167

Times Cited Count：2 Percentile：6.66(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.

Journal Articles

Generation of radial electric field induced by collisionless internal kink mode with density gradient

Matsumoto, Taro; Tokuda, Shinji; Kishimoto, Yasuaki; Naito, Hiroshi*

Physics of Plasmas, 10(1), p.195 - 203, 2003/01

https://doi.org/10.1063/1.1528608

Times Cited Count：5 Percentile：16.70(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.

Journal Articles

Effects of circulating energetic ions on sawtooth oscillations

Wang, S.; Ozeki, Takahisa; Tobita, Kenji

Physical Review Letters, 88(10), p.105004_1 - 105004_4, 2002/03

https://doi.org/10.1103/PhysRevLett.88.105004

Times Cited Count：22 Percentile：70.93(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.

Journal Articles