Anomalous tungsten transport driven by ion temperature gradient turbulence

Abstract

The present study reveals that the anomalous tungsten particle transport based on the nonlinear gyrokinetic simulations shares some similarities with that of the linear gyrokinetic study, meanwhile there exists some significant differences. In particular, nonlinear excitation of the linearly stable modes plays a non-negligible role in the anomalous tungsten particle transport. The highlighted results are the downshift of the critical density gradient for zero tungsten particle transport and the modification of the poloidal profile of the outward tungsten particle transport, which are both related to the small scale turbulent fluctuations. The former one is due to the outward particle convection produced by the linearly stable modes. The later one is brought by both the linearly stable modes and the large-scale eddies with finite ballooning angle, which flatten the poloidal profile of the particle diffusion and further shift the peak positions of the strongest outward particle transport to the high poloidal angle regions.