Heat Transport in Off-axis EC-Heated Discharges in DIII-D

In low-density H-mode discharges in DIII-D, ECH applied off-axis produces electron temperature profiles with strong peaking at the heating location and very slow penetration of heat into the core. This type of discharge is a counter example to the heat-pinch effect normally seen in tokamaks where off-axis heating propagates rapidly to the center. In a recent experiment on DIII-D, the conditions for producing these ``bat-eared" $T_e$ profiles were studied. It was observed that H-mode is a necessary condition; L-mode discharges exhibit the classic heat pinch. A region of low transport corresponds to the $q=1$ surface as verified by the sawtooth inversion radius. Results of transport analysis are presented as well as measurements of $n_e$ and $T_e$ fluctuations.