Spatiotemporal structure of resistive pressure-gradient-driven turbulence

High-resolution turbulence calculations are needed to characterize the resistive pressuregradient-driven turbulence in toroidal geometry because the wave number spectrum is very broad with a low decay index. Here, two main issues are addressed: the spatiotemporal structure of the turbulence and the validity of the mixing-length approach for toroidal geometry. Well above the instability threshold, steady-state turbulence is established. In this case, the relevant spatial scales are the width of the individual poloidal components of the ballooning mode, instead of the toroidal scale lengths. The situation is reversed near the instability threshold, where the stationary state can be dominated by one toroidal mode.