Electron Temperature Turbulence and Poloidal Turbulent Flow in Negative Triangularity Plasmas on DIII-D

The reactor-relevant negative triangularity (-$\delta )$ shape recently achieved in the DIII-D Tokamak is potentially a good candidate for future fusion reactors. It generally has an energy confinement similar to H-mode plasmas in conventional positive triangularity ($+\delta )$ shape but without ELMs. This work presents electron temperature turbulence and poloidal turbulent flow in -$\delta $ plasmas on DIII-D for understanding their transport and confinement properties. In an Inner Wall Limiter (IWL) configuration with an L-mode edge, the core electron temperature turbulence level in -$\delta $ shape is similar to or slightly less than a $+\delta $ L-mode in the IWL configuration, but near the separatrix the -$\delta $ shape has much lower (\textasciitilde 40{\%}) turbulence. The poloidal turbulent flow for IWL plasmas (both -$\delta $ and $+\delta )$ shows no strong velocity shear contrary to conventional $+\delta $ H-mode plasmas. However, in an L-mode diverted configuration a slight well in the edge poloidal velocity is observed in the -$\delta $ shape, and the electron temperature turbulence level is lower from the edge to the core compared to the IWL case. Interestingly, as the plasma goes into an ``H-mode like'' condition, the edge velocity well becomes much deeper, while electron temperature fluctuation level is not reduced.