Gyrokinetic simulations of DIII-D near-edge L-mode plasmas*

In order to understand the L-H transition, a good understanding of the L-mode edge region is necessary. We perform nonlinear gyrokinetic simulations of a DIII-D L-mode discharge with the GENE code in the near-edge, which we define as $\rho_{tor}\ge 0.8$. At $\rho =0.9$, ion-scale simulations reproduce experimental heat fluxes within the uncertainty of the experiment. At$\thinspace \rho =0.8$, electron-scale simulations reproduce the experimental electron heat flux while ion-scale simulations do not reproduce the respective ion heat flux due to a strong poloidal zonal flow. However, we reproduce both electron and ion heat fluxes by increasing the local ion temperature gradient by $80\% $. Local fitting to the CER data in the domain $0.7\le \thinspace \rho \le 0.9$ is compatible with such an increase in ion temperature gradient within the error bars. Ongoing multi-scale simulations are investigating whether radial electron streamers could dampen the poloidal zonal flows at $\rho =0.8\thinspace $and increase the radial ion-scale flux.