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 gradient in confined plasmas is studied in a sheared slab magnetic configuration. The turbulence drive from the temperature gradient and parallel 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 framework 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 coefficients that include the pinch effects are computed. Correlations with tokamak experimental observations such as an isotope scaling of plasma confinement time are discussed. (C) 1997 American Institute of Physics.