Anomalous transport theory for toroidal helical plasmas

Anomalous transport coefficients in toroidal helical plasmas are studied on the basis of a new theoretical method. Self-sustained turbulence is analyzed by balancing the non-linear growth due to current diffusivity with the non-linear damping by ion viscosity and thermal conductivity. Interchange and ballooning mode turbulence is investigated, and the geometrical difference of the anomalous transport coefficient is clarified. Variation of transport due to the geometrical difference in toroidal helical plasmas is illustrated. A mechanism for confinement improvement is searched for. To verify the non-linear destabilization and the self-sustained state, a non-linear simulation of the interchange mode turbulence is performed in a sheared slab. It is demonstrated that non-linear enhancement of the growth rate occurs when the fluctuation amplitude exceeds a critical level. In the saturation stage, the fluctuation level becomes higher, in conjunction with the enhanced non-linear growth. (author). 13 refs, 5 figs, 1 tab