Development of burning plasma and advanced scenarios in the DIII-D tokamak

Abstract

Significant progress in the development of burning plasma scenarios, steady-state scenarios at high fusion performance and basic tokamak physics has been made by the DIII-D team. Discharges similar to the ITER baseline scenario have demonstrated normalized fusion performance nearly 50% higher than the value specified for Q = 10 in ITER reference scenario, under stationary conditions. Discharges have also been demonstrated in DIII-D with enhanced performance under stationary conditions that project to Q similar to 10 for longer than 1 h in ITER at reduced current, if such a mode of operation can be realized in ITER. Proof of high fusion performance with full noninductive operation has been obtained. Underlying this work are studies validating approaches to confinement extrapolation, disruption avoidance and mitigation, tritium retention, edge localized mode avoidance and operation above the no-wall pressure limit. In addition, the unique capabilities of the DIII-D facility have advanced studies of the sawtooth instability with unprecedented time and space resolution, threshold behaviour in the electron heat transport, rotation in plasmas in the absence of external torque, measurements in the edge pedestal region and plasma fuelling. Understanding these phenomena at a fundamental level contributes to development and ultimately the optimization of tokamak scenarios.