THEORY OF RESISTIVITY-GRADIENT-DRIVEN TURBULENCE IN THE PRESENCE OF FLOW

The resistivity-gradient-driven turbulence is investigated in the pres ence of both poloidal and parallel/toroidal hows. At saturation, the p oloidal how shear reduces fluctuations st the edge of plasmas, the par allel flow and its shear both reduce fluctuations in the core of plasm as. This indicates that the mechanism for a high confinement regime (H mode) may be the turbulence suppression due to the poloidal flow shew 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.