DIII-D advanced tokamak research overview

Recent progress in the development of long pulse, high performance discharges on the DIII-D tokamak is reviewed. This is highlighted by a discharge achieving simultaneously a bN H of 9, bootstrap current fraction of 0.5 and non-inductive current fraction of 0.75, sustained for 16 energy confinement times. The physics challenge has changed in the long pulse regime. Non-ideal MHD modes limit the stability, fast ion driven modes may play a role in fast ion transport, which limits the stored energy, and plasma edge behaviour can affect the global performance. New control tools are being developed to address these issues.