Constraints on divertor heat flux width at high power and plasma density in DIII-D H-mode plasmas

Near scrape-off layer (SOL) plasma profiles in DIII-D are examined for constraints on divertor heat flux width at high power and plasma density. Both MHD stability and turbulence have been conjectured to broaden divertor heat flux profiles at the high plasma density associated with divertor detachment for high power discharges. The high heating power, plasma density and energy confinement of the Super-H regime make it an attractive platform for studying divertor heat flux width scaling. Near SOL density, temperature and pressure gradients from Thomson scattering are compared to MHD ballooning limits and other turbulence drive parameters as a function of density at high power. Super-H profiles at high plasma current, ≤ 1.9 MA, and high power, ≤ 15 MW, are compared to previous analysis in standard H-mode plasmas at lower plasma current and heating power. The previous standard H-mode analysis did observe SOL heat flux, though separatrix pressure gradients were measured at up to twice the ideal MHD ballooning limit. Projecting SOL heat flux broadening to future reactor-scale tokamaks could allow for effective divertor heat flux dissipation at lower plasma and impurity density than could otherwise be achieved.