Gyrokinetic study of impurity transport in the H-mode pedestal

We investigate ion-scale turbulent transport in the edge pedestal of DIII-D H-mode plasmas and the impact of impurities. In the H-mode pedestal, we find that for the ITG modes the carbon impurity has a negligible effect on the instability, but for the TEM-like modes it can have a significant impact with growth rates decreasing by ~40% compared to a pure deuterium plasma. At low k_yρ_i ( 0.1≤ k_yρ_i ≤1.5) the most unstable eigenmode is an ion mode with positive frequency (ITG-like), with electron mode (TEM-like) with negative frequency at higher k_yρ_i ( 1.6≤ k_yρ_i ≤2.0). Here, linear gyrokinetic calculations are first carried out for inter-ELM DIII-D H-mode discharges during the buildup of the pedestal to investigate turbulent transport at three radial locations ρ_tor= 0.80, 0.85 and 0.90 using the gyrokinetic code GENE in the local limit. Following this, the quasilinear (QL) fluxes will be calculated and compared to nonlinear fluxes to test the validity of quasilinear approximation. Finally, QL fluxes will be compared with GENE neoclassical fluxes to quantify the importance of anomalous transport levels.