Gyro-kinetic Simulations of Internal Collapse in Reversed Magnetic Shear Tokamak
T.Matsumoto1), H.Naitou2), S.Tokuda1), Y.Kishimoto1)
1) Naka Fusion Research Establishment, JAERI, 801-1 Mukoyama, Naka-machi, Ibaraki 311-0193, Japan
2) Department of Electrical and Electronic Engineering, Yamaguchi Univ. 2-16-1 Tokiwadai, Ube city 755-8611, Japan
Abstract.
The gyrokinetic particle simulation and the gyro-reduced MHD simulation are executed to clarify the kinetic modifications of the MHD phenomena in the reversed shear configuration (RSC) of a tokamak plasma. The kinetic (collisionless) double tearing modes in the RSC, which is destabilized not by the resistivity but by the electron inertia, are found to grow up at the Alfven time scale by the coupling of two perturbations originated in each resonant surface. It is also found that the internal collapse occurs at the Alfven time scale. After the internal collapse, the secondary reconnection is induced by the m/n=2/1 flow. As a result of current reconcentration, a reversed shear configuration with q<2 is constructed again.