Overview of Recent DIII-D Experimental Results

DIII-D experiments have demonstrated the effectiveness of recent upgrades in assessing key fusion science and ITER physics issues. These upgrades include: 1)~the reorientation of a neutral beam to allow co-, counter-, and balanced injection, 2)~the modification of the lower divertor to allow particle exhaust in high triangularity, double-null (DN) configurations, 3)~modification of the current feeds for the toroidal field and 4)~high-bandwidth power supplies for controlling the internal asymmetric coil set. Using these tools, experiments have demonstrated the capability to maintain near zero toroidal rotation, density control in a wide range of plasma shapes, and a reduction in both the intrinsic and corrected error fields. H-mode confinement is observed to decrease slightly as toroidal rotation decreases, yet the best cases with near-zero rotation is better than the scaled confinement needed for ITER ($H_{98y2}=1.2$). Advanced Tokamak experiments have shown the benefit of DN operation in achieving high $\beta$, and edge localized mode suppression in the ITER shape at low collisionality using resonant magnetic perturbations was demonstrated.