Characterizing near-edge DIII-D L-mode plasmas with gyrokinetic GENE simulations*

Studying the L-mode edge is an important prerequisite for understanding the L-H Transition. Moreover, correctly predicting L-mode profiles is important for vertical stabilization of the plasma during current ramp-up and ramp-down phases of ITER. Here we present nonlinear gyrokinetic simulations with GENE of a DIII-D L-mode plasma in the near-edge, which we loosely define as 0.80 ≤ ρ ≤ 0.95. We have previously reported on flux-matched single-scale simulations at ρ=0.80. These have been followed up by multi-scale simulations, which indicate that a widely used heuristic rule on the importance of multi-scale effects is on the cautious side: Preliminary results show that single-scale simulations are sufficient when multi-scale effects were expected. At ρ=0.90, single-scale flux-matched simulations indicate that the E×B shearing rate plays an important role already in the near-edge and is predicted to become increasingly important in the edge-region of L-mode plasmas. Linear and non-linear simulations at ρ=0.95 are currently underway and will be presented.