The Role of Heating Power in Tungsten Transport to Collector Probes in the Scrape-off Layer of DIII-D

Modeling results are presented for scrape-off layer (SOL) transport of tungsten (W) sputtered from the DIII-D divertor for two discharges differing by twice the heating power, P_heat. Results show that W deposition on a collector probe at the outer midplane (OMP) increases with P_heat due to a combination of increased physical sputtering and enhanced SOL transport, in particular the radial and parallel transport near the divertor. Two H-mode discharges in the 2016 DIII-D Metal Rings Campaign had similar plasma conditions and magnetic geometry, but differed mainly by a doubling of P_heat and ELM frequency. An OMP collector probe measured significantly more W for the higher P_heat shot, with most of the additional W on the side facing toward the outer target along the magnetic field (the outer-target-facing (OTF) side). Spectroscopic sourcing data from a WI emission line showed significantly more sputtering for the higher P_heat shot. Each discharge was simulated using the OEDGE code package. The simulated transport of W ions showed that enhanced SOL transport between the divertor target and the OTF side of the collector probe is consistent with the observed deposition patterns.