Leveraging Peeling Pedestal Physics in the Super H-Mode as a Platform for Integrated Core-Edge Studies

DIII-D experiments assess compatibility of Super H-mode (SH) pedestals with high divertor radiation using advanced feedback algorithms for density and radiated power control with impurity seeding. The SH regime, with a current-limited pedestal, allows co-optimization of important parameters for future devices such as pedestal pressure, collisionality and separatrix density. Four optimization avenues for core edge integration have been developed: 1) divertor-focused solution with N2 seeded partially detached plasmas in an open divertor with ~25% degradation to core performance; 2) high recycling open divertor at the onset of detachment with modest penalties (<5%) to core performance, 80% radiated power fraction, 3) closed divertor SH plasmas at detachment onset, and 4) core-focused solution with a modestly cooled, attached open divertor. The high recycling divertor at detachment onset maximizes confinement on closed flux surfaces while providing a target plasma for testing high heat flux scenarios on various divertor configurations. The SH pedestal in the closed divertor is more resilient to D2 puffing than the open divertor, showing less degradation with increased gas. EPED predictions are consistent with experimental pedestal stability, but work is needed to extend stationarity.