High Performance Core-Edge Solutions in Super H-Mode

The Super H-Mode (SH) regime is predicted to enable pedestal height and fusion performance substantially higher than standard H-mode operation. This regime exists due to a bifurcation of the pedestal pressure as a function of density, predicted by the EPED model to occur in strongly shaped plasmas above a critical density. The SH regime can have pedestal pressure twice as high, and collisionality 4x lower, than the standard H-mode at the same density. Because the pedestal in SH mode is limited by current-driven modes, increasing the near separatrix density to enable attractive divertor solutions is predicted to be compatible with high fusion performance in the core (unlike in standard H-modes). DIII-D SH experiments have achieved record levels of fusion gain on a medium scale tokamak, and have sustained high performance using 3D magnetic perturbations. New experiments have employed D₂ and N₂ gas to improve divertor conditions. High pedestal pressure (>20kPa) and core confinement (τ_E~.15s) are sustained across a 30x gas scan, and with a strongly radiating divertor with a 3x reduction in divertor T_e. We discuss DIII-D results, and further predictions for DIII-D and ITER.