Turbulence, Transport and Energy Confinement Dependence on Plasma Current in DIII-D

The measured characteristics of long-wavelength turbulence vary strongly with q$_{\mathrm{95}}$, including the normalized fluctuation amplitude profile 0.45\textless r/a\textless 0.9 increasing strongly with q$_{\mathrm{95}}$. This is demonstrated by a systematic variation of the plasma current while other global parameters are held nearly fixed. Multichannel transport changes consistently, with both reduced thermal energy and momentum transport at lower q$_{\mathrm{95}}$. This dependence is observed in the core of L-mode and hybrid H-mode regimes. Correlation lengths and decorrelation times of turbulence show weaker variation with q$_{\mathrm{95}}$. Zonal flows decrease in amplitude, while Geodesic Acoustic Modes (GAM) increase in amplitude with q$_{\mathrm{95}}$ in L-mode, qualitatively consistent with theoretical predictions. Empirical scaling relations show that energy confinement time depends approximately linearly on plasma current in regimes with monotonically increasing q-profiles. Given this strong dependence of transport and confinement on plasma current, it is critical to understand the relationship of turbulence on q$_{\mathrm{95}}$, as well as the q-profile shape, to identify regimes of improved performance with optimized q-profiles. Initial results from TGLF modeling will be presented with the experimental data.