Towards Demonstration of Steady-State High-Performance Scenarios in DIII-D

Experiments on advanced scenarios in DIII-D are focused on extension to the resistive time scale, optimization, and exploration for higher performance. Optimization studies use ECCD and counter-NBI to modify the $q$ profile shape, looking at the effect on MHD stability and bootstrap current. Feedback control of the current formation is also a key element of optimization. Closed-loop experiments and modeling of open-loop tests have been carried out. Experiments seeking $\beta _{N}$=5 used two approaches -- high $q_{min}$ with rotational stabilization and high magnetic shear. High shear experiments achieved $\beta _{N}$~$>$~4.5 transiently. Attempts to use the longer-pulse (5 s) ECCD system to extend the duration of noninductive high-performance discharges to resistive equilibrium will be presented.