Modelling of tungsten prompt redeposition at the inner wall of ITER during ramp-up

• Tungsten prompt redeposition profiles at inner wall have been modelled with ERO for ITER ramp-up phase using background plasma from SOLPS-ITER. • Prompt-redeposition profiles are peaked at the tangency point. • Maximum fraction of prompt redeposition varies between 60 % and 80 %, dependent on plasma parameters and assumption for tungsten cross-field diffusion. • Prompt redeposition profiles can be used as input for plasma background codes to improve the assumption of net tungsten source. The prompt redeposition of sputtered tungsten at the inner wall of ITER during current ramp-up has been simulated with the ERO code. Plasma parameters from SOLPS-ITER for a medium-density (with a peak electron density of 4E12 cm −3 at the inner wall) and a high-density (1E13 cm −3 ) case have been used as input for ERO. Simulations without anomalous cross-field diffusion for sputtered tungsten ions reveal peaked prompt redeposition profiles in poloidal direction. At the tangency point with largest electron temperature and density, maximum prompt redeposition fractions of about 60 % for the medium density and 80 % for the high density case occur. At a distance of 50 cm away from the tangency point, prompt redeposition decreases to 10 % (medium-density) and 20 % (high-density case). The simulations without anomalous cross-field diffusion show that the overall redeposition is the same as the prompt redeposition thus the overall redeposition is only due to prompt redeposition. An anomalous cross-field diffusion of 1 m 2 /s leads to slightly increased prompt redeposition, however, for both medium and high-density case there is now also a significant amount of non-prompt redeposition. The modelled profiles of prompt redeposition can be used as input for plasma simulation codes like SOLPS-ITER to improve the assumptions of net tungsten wall sources.