Particle transport in density gradient driven TE mode turbulence

Journal article, 2012

The turbulent transport of main ion and trace impurities in a tokamak device in the presence of steep electron density gradients has been studied. The parameters are chosen for trapped electron mode turbulence, driven primarily by steep electron density gradients relevant to H-mode physics. Results obtained through nonlinear and quasilinear gyrokinetic simulations using the GENE code are compared with results obtained from a fluid model. Impurity transport is studied by examining the balance of convective and diffusive transport, as quantified by the density gradient corresponding to zero particle flux (impurity peaking factor). Scalings are obtained for the impurity peaking with the background electron density gradient and the impurity charge number. It is shown that the impurity peaking factor is weakly dependent on impurity charge and significantly smaller than the driving electron density gradient.