Pedestal fueling through interpretive analysis of measured main chamber and divertor target flux in DIII-D

Fueling of the pedestal from divertor and main chamber recycling in DIII-D is assessed by a combination of experimental measurements, plasma modeling and kinetic neutral analysis. The 2D profile of surface recycling between edge localized modes in H-mode was previously determined in DIII-D from surface mounted Langmuir probes and a plasma configuration where toroidally symmetric recycling was dominant. The measured profile of recycling neutrals is launched by the DEGAS2 code into a 2D background plasma profile reconstructed by the UEDGE fluid model and constrained to match the upstream temperature and density profiles. Divertor plasmas of varying density and temperature are constructed to test sensitivity to uncertainty in the divertor plasma conditions. The pedestal ionization rate from this analysis can match the inferred outward ion flux across separatrix only for high density, detached inboard divertor conditions.