Global tungsten erosion and migration modeling for the EU-DEMO with the ERO2.0 code

Global tungsten migration, thus erosion, transport, and deposition, in the EU-DEMO tokamak is investigated using ERO2.0 simulations for an argon-seeded ELM-free H-mode plasma scenario with expected 2 GW fusion power developed with the narrow-grid version of the SOLPS-ITER code. The tungsten erosion calculations by the plasma background include contributions from all ionic charge states of deuterium, helium, and argon, as well as deuterium charge-exchange neutrals. The latter is estimated in the framework of advanced kinetic energy spectra recorded at various poloidal locations across the device. Since the SOLPS-ITER plasma solution demands an extrapolation of plasma parameters up to first wall panels made of tungsten, different assumptions on the far-SOL plasma temperature profiles ranging from 2 eV to about 10 eV are applied in order to study their impact on tungsten erosion and transport on EU-DEMO. The simulations reveal that main chamber erosion is dominated by charge-exchange neutrals for very cold far-SOL conditions of 2 eV, while it is driven by argon ions and tungsten self-sputtering when going to higher temperatures. This is different for the semi-detached divertor, where the erosion is clearly dominated by argon ions in all cases. The ratio between divertor to main chamber source is found to decrease from roughly 10 to 3 with increasing far-SOL temperature. A net main chamber to divertor transport of tungsten is observed and explained by long ionization mean free paths of sputtered tungsten atoms, ranging from 50% and 39% for the applied [T e, T i] far-SOL assumptions.