Documentation and Search for Missing Near Edge \mbox{L-mode} Transport

While GYRO simulations of the core ($0 < r/a < 0.7$) in typical DIII-D L-modes seems to be in good agreement with experiment, local GYRO simulated low-$k$ ($k_\theta\rho_s<1$) transport and turbulence intensity is about 5-fold lower than experimentally inferred levels in the near edge L-mode ($r/a=0.7-0.95$) DIII-D shot 128913 [1]. Global slice GYRO simulations of this and other well-studied discharges [2] are presented here to further document the shortfall. TGLF transport simulations over a large L-mode database indicate this short fall is not atypical and L-modes easily transit to H-like profiles. High edge e-i collisionality stabilizes the TEM modes so that $\chi_\epsilon$ decreases like T$^{7/2}/n$ to the cold edge. The very high magnetic shear stabilizes the ITG despite the very high temperature gradient drive and high $q$. High-$k$ ETG can make up for the shortfall in the electron but not the ion channel. Near edge L-mode transport is highly local. Artificially large edge damping of the zonal flows/GAMs helps only somewhat.\par \vskip6pt \noindent [1] C.~Holland, A.E.\ White, et~al., Phys.\ Plasmas {\bf 16}, 052301 (2009).\par \noindent [2] R.E.~Waltz, et al., Phys.\ Plasmas {\bf 13}, 072304 (2006).