DIVIMP simulation of W transport in the SOL of JET H-mode plasmas

This study provides predictions of tungsten contamination extrapolated from an inter-edge localized mode phase of a high-triangularity, high-confinement, ITER-like wall (ILW) reference plasma without impurity seeding in JET. The tungsten concentrations for equivalent ILW plasmas are predicted for low, medium and high upstream densities, utilizing the Monte Carlo trace-impurity code DIVIMP on background plasmas calculated with the two-dimensional fluid code EDGE2D/EIRENE. It is observed that operation at the low-upstream-density plasma with a sheath-limited scrape-off layer leads to a core tungsten concentration of the order of 10 ^-5. Increasing the density leads to a high-recycling scrape-off layer with sufficient divertor retention to ensure an acceptable core tungsten concentration that is less than 10 ^-5. Sufficient divertor retention is achievable if the peak target electron temperature, T _e, is below 10 eV. Achieving a significant reduction in tungsten sputtering by multiple charged impurity species (e.g. Be ²⁺ and C ⁴⁺) requires a peak target T _e below 5 eV, which requires strong divertor radiation, achieved by impurity seeding in the ILW configuration.