Electrostatic turbulence and transport with stochastic magnetic field lines

Electrostatic turbulence, associated convective transport and sheared flows at the edge of a tokamak plasma are strongly affected by magnetic perturbations with field line stochastization. Results from three dimensional numerical simulations of flux driven resistive ballooning turbulence are presented showing that (a) the level of convective flux associated with fluctuations is not quenched by the magnetic field perturbation despite a reduced pressure fluctuation level and (b) the poloidal plasma rotation is suppressed and zonal flows are reduced by an anomalous friction due to stochasticity. This inhibits the self regulation mechanism of large scale transport events and bursts are found to resist the magnetic perturbation. (author)