Theory of Resistivity-Gradient-Driven Turbulence in the Presence of Flow

The resistivity-gradient-driven turbulence is investigated in the presence of both poloidal and parallel/toroidal flows. At saturation, the poloidal flow shear reduces fluctuations at the edge of plasmas, the parallel flow and its shear both reduce fluctuations in the core of plasmas. This indicates that the mechanism for a high confinement regime (H mode) may be the turbulence suppression due to the poloidal flow shear at the edge of plasmas, and the mechanism for a very high confinement (VH mode) may be the turbulence suppression due to the toroidal flow and its shear in the core of plasmas.