Tearing Mode Instability due to Anomalous Resistivity

Abstract

Tearing mode instability in the presence of microscopic turbulence is investigated. The effects of microscopic turbulence on global MHD mode are taken as drags which are calculated by one-point renormalization method and mean-field approximation. These effects are reduced to effective ion viscosity, resistivity and thermal conductivity in reduced MHD equations. Using these equations, the stability analyses of the tearing mode are performed. It is shown that a finite amplitude of fluctuation enhances the growth rate of tearing mode. For very high values of turbulent diffusivities, marginally stable state exists. The effects of each turbulent diffusivity on mode stability are examined near marginal stability boundary. Parameter dependence on the growth rate of tearing mode is analyzed with/without the microscopic turbulence. For the microscopic turbulence, a resistive ballooning mode (RBM) turbulence and ion temperature gradient (ITG) turbulence are considered as examples.