(TH/P3-3) High-m Multiple Tearing Modes in Tokamaks: MHD Turbulence Generation, Interaction with the Internal Kink and Sheared Flows

S. Hamaguchi1), A. Bierwage2), S. Benkadda3), M. Wakatani2), Q. Yu4)
1) Osaka University, Suita, Osaka, Japan
2) Kyoto University, Uji, Kyoto, Japan
3) University of Provence, Marseille, France
4) Max-Planck Institute for Plasma Physics, Garching, Germany

Abstract.  Linear instability and nonlinear dynamics of multiple tearing modes (MTMs) are studied with a reduced magnetohydrodynamic (RMHD) model of a large-aspect-ratio tokamak plasma in the limit of zero pressure. When low-order rational surfaces (such as those for q = 1 or 2 with q being the safety factor) are in close proximity, tearing modes on the rational surfaces are strongly coupled and exhibit a broad spectrum of positive growth rates with dominant mode numbers around mPeak∼10. It is shown that collisionless double tearing modes (DTMs) due to electron inertia also have similar linear stability characteristics. Nonlinear dynamics associated with fast growing high-m MTMs can affect the evolution of low-m modes. For example, resistive q = 1 triple tearing modes (TTMs) generate MHD turbulence in a disrupted annular ring and the turbulence can impede the growth of an internal kink mode at a finite amplitude. Possible interactions between MTMs and sheared zonal flow are also discussed.

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