TH/P8-8 Influence of RF Fields on Anomalous Impurity Transport in Tokamaks

Trace impurity transport in tokamaks is studied using an electrostatic, collisionless fluid model for Ion-Temperature-Gradient (ITG) and Trapped-Electron (TE) mode driven turbulence in the presence of radio frequency (rf) fields in the ion cyclotron range of frequencies, and the results are compared with neoclassical predictions. Two separate effects of the rf field on ITG/TE-mode stability and impurity transport are considered, namely an incoherent interaction between a fast magnetosonic source wave and ITG modes; and the ponderomotive force associated with the rf field of the fast magnetosonic wave. It is shown that the trace impurity transport can be affected by the rf fields. However, the impurity diffusivity and convective velocity (pinch) are usually similarly affected and hence the steady state impurity density peaking factor -∇nz/nz is only moderately affected by the rf fields.