Impact of large island perturbations on turbulent blob transport in tokamaks

The turbulent blob transport in the tokamak edge and its structural changes in perturbed magnetic configurations like islands and ergodic structures is studied by means of numerical simulations. An explicit finite-difference algorithm for treating three-dimensional plasma fluid turbulence models is presented and described in detail. For an unperturbed magnetic equilibrium the numerical results show an appearance of density blobs in the vicinity of the last closed flux surface. In the presence of an ergodic magnetic perturbation strong suppression of blob amplitudes and local reversal of the radial ExB-flux close to the resonances is observed. (C) 2007 American Institute of Physics