Nonlinear Simulation of Kinetic Internal Kink Modes in Tokamaks

H. Naitou, J.-N. Leboeuf1), H. Nagahara, T. Kobayashi2),
M. Yagi3), T. Matsumoto4), S. Tokuda4)

Electrical and Electronic Engineering, Yamaguchi University, Ube 755-8611, Japan
1)Physics and Astronomy, University of California at Los Angeles, CA 90095-1547, USA
2)Media and Information Technology Center, Yamaguchi University, Ube 755-8611, Japan
3)Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
4)Naka Fusion Research Establishment, Japan Atomic Energy Research Institute, Ibaraki 816-8580, Japan


Kinetic modifications of MHD modes introduce new paradigms in MHD theory. Previous studies of the (collisionless) m=1/n=1 kinetic internal kink mode with electron diamagnetic effects revealed that there is a weakly unstable mode even in the region in which theory predicts complete stabilization [1,2]. The mode pattern has m=1 sheared poloidal flow which generates vortices due to the Kelvin-Helmholz instability [3]. These studies have been carried out in cylindrical geometry using the gyro-reduced-MHD(GRM) code. The relevance to toroidal geometry is quite critical to the theory of the sawtooth crash because the mode-coupling due to toroidal effects may dominate the nonlinear development of the instability. A modified version of the FAR code including kinetic effects is being developed to study the effect of vortex generation on the internal kink mode. In the cylindrical limit, the linear mode pattern and the complex frequency obtained with the modified FAR code coincide with the results obtained with the GRM code. Comparative results of nonlinear calculations in cylindrical and toroidal geometries will also be reported.

References

[1] H. Naitou, T. Kobayashi, T. Kuramoto, S. Tokuda, T. Matsumoto, J. Plasma Fusion Res. SERIES 2 (1999) 259.
[2] H. Naitou, T. Kuramoto, T. Kobayashi, M. Yagi, S. Tokuda, T. Matsumoto, J. Plasma Fusion Res. 76 (2000) 778.
[3] H. Naitou, T. Kobayashi, M. Yagi, T. Matsumoto, S. Tokuda, Y. Kishimoto, Book of Abstracts, 19th IAEA Fusion Energy Conference (Lyon, France, 14-19 October 2002) p.138.