Transport Analysis and Turbulent Ion Fluctuation Measurements with UF-CHERS at T$_{\mathrm{e}}$/T$_{\mathrm{i}}$ \textasciitilde 1 in DIII-D
POSTER
Abstract
Radial profiles of multi-field fluctuation measurements (n$_{\mathrm{C}}$, T$_{\mathrm{i}}$, V$_{\mathrm{tor}})$ were obtained with the Ultra Fast Charge Exchange Recombination Spectroscopy (UF-CHERS) diagnostic in a DIII-D experiment studying L-mode turbulent transport at near-unity T$_{\mathrm{e}}$/T$_{\mathrm{i}}$ ratio. For a 10-20{\%} increase in T$_{\mathrm{e}}$/T$_{\mathrm{i}}$ using electron cyclotron heating, analysis of UF-CHERS measurements revealed a radially varying increase in normalized T$_{\mathrm{i}}$ fluctuations of \textasciitilde 1-3{\%} of the equilibrium value, a corresponding decrease in V$_{\mathrm{tor}}$ fluctuations, and little change in n$_{\mathrm{C}}$ fluctuations. The same trend is also observed at increased density/collisionality. ONETWO transport analysis found increased electron and ion energy transport with larger T$_{\mathrm{e}}$/T$_{\mathrm{i}}$, consistent with the measured increase in T$_{\mathrm{e}}$ and T$_{\mathrm{i}}$ fluctuations. TGLF analysis showed increased growth rate for the most dominant modes at higher T$_{\mathrm{e}}$/T$_{\mathrm{i}}$ over the wavenumber range (0.1 $\le $ k$_{\mathrm{\theta }}\rho_{\mathrm{s}} \quad \le $ 10) encompassing UF-CHERS' sensitivity. TGLF also calculated increased T$_{\mathrm{i}}$ fluctuations at higher T$_{\mathrm{e}}$/T$_{\mathrm{i}}$. Further comparisons between experimentally inferred transport, multifield turbulence measurements, and transport models will be presented.
*Work supported by US DOE under DE-FG02-08ER54999, DE-FC02-04ER54698, and NSF GRFP grant DGE-1256259.