Characterization of electrostatic turbulent fluxes in tokamak edge plasmas

A parametrization is presented for the transport from electrostatic turbulence in tokamak edge plasmas. Employing a nonlinear drift wave turbulence simulation, transport coefficients are obtained as functions of a density gradient, temperature gradients, and an external ExB shear parameter. An external radial electric field, E-r, is passed to the turbulence model as a background ExB shear flow which suppresses the radial flux together with the Reynolds stress induced electric fields. In a multidimensional parameter space, the transport coefficients exhibit a nonmonotonic dependence on the density and temperature gradients that is unique to the low to high confinement transition. (C) 2004 American Institute of Physics.