Turbulence from inverted density-to-temperature gradients in LHD

Recent experiments in Large Helical Device(LHD) show interesting ``ears'' in the plasma density profiles -- density peaks at $r/a\approx 0.8$. The local maximum produces an inner region with negative $\eta_e=L_n/L_T$ and an outer region with positive $\eta_e$. The linear analysis shows that electron temperature gradient(ETG) mode is very unstable in the negative $\eta_e$ region. We perform gyrokinetic simulations of ETG modes in cylinderical geometry with and without curvature effects using density and temperature profiles from LHD experiments. Fluctuations measured by 2D-PCI also found the waves rotating in the electron direction inside the ear and in the ion direction outside the density ear as expected from the dispersion relation and standard radial electric field in these discharges. We also investigate ITG/TEM and other possible modes in these experiments.