Advances in the Physics Basis of the Hybrid Scenario on DIII-D

Recent experiments on DIII-D have extended the hybrid scenario towards the burning plasma regime by incorporating strong electron heating, low torque injection, and edge localized mode (ELM) suppression. Hybrid performance projecting to Q 10 on ITER at q95=3.1 has been achieved in plasmas with reduced ion/electron temperature ratio or Mach number. Confinement is decreased relative to previous hybrid results, consistent with measurements of increased turbulence at low and intermediate wavenumbers. For the first time, large type-I ELMs have been completely suppressed in a hybrid plasma at q95=3.6 by applying edge resonant magnetic perturbations (RMPs) with toroidal mode number n=3. Additionally, high performance hybrid and steady-state scenario operation has been demonstrated with reduced frequency of wall conditioning with a >95% graphite plasma-facing wall.