TURBULENT PARTICLE-TRANSPORT IN TOKAMAK PLASMAS WITH IMPURITIES

The turbulence driven by the ion temperature gradient, the mass shear flow parallel to the magnetic field, and the impurity ion density grad ient in confined plasmas is studied in a sheared slab magnetic configu ration. The turbulence drive from the temperature gradient and paralle l shear flow of the majority ion component is shown to be enhanced by the shear flow and negative density gradient of the impurity ions. The particle diffusion induced by the turbulence is obtained within the f ramework of quasilinear fluid theory. Optimal transport parameters for an inward ''pinch'' of the majority ions and the outward flow of the impurity ions are determined. The corresponding effective diffusion co efficients that include the pinch effects are computed. Correlations w ith tokamak experimental observations such as an isotope scaling of pl asma confinement time are discussed. (C) 1997 American Institute of Ph ysics.