Core Turbulence and Flow Dynamics Across L-H Transition on DIII-D

First measurements of core low and intermediate-k correlation lengths as well as the dynamic turbulence amplitude behavior across near-balanced NBI-heated L- to H-mode transitions have been obtained on DIII-D. In these discharges, poloidal turbulence flow increases with little change in its shear as the L-H transition is approached. Leading up to the transition, fluctuation levels $(\tilde n/n)$ of low-k ($<$3 cm$^{-1}$) show little variation, while that of intermediate- (3$-$6 cm$^{-1}$) and high-k ($\sim$ 35 cm$^{-1}$) increase. At the same time, core radial correlation lengths of both low and intermediate-k decrease. In contrast, electron temperature fluctuation levels $(\tilde T_e/T_e)$ first increase then drop. With these data a multi-scale and multi-field picture of the L to H transition dynamics is being developed allowing detailed comparison to theory and simulation (e.g. linear gyrokinetic stability simulations, TGLF).