Simulated effects of W dust ablation and deposition on the pedestal edge in JET D and DT experiments

Abstract

A modelling analysis is performed on JET D and DT discharges, where W dust inux across the separatrix, in the pedestal edge region may a ect L-H-L mode transition. The experimental basis of the proposed approach stems from the observation that transient impurity events (TIEs) are often associated with the presence of a shower of particles seen in the camera images and with strong optical emission. If the localised source of radiation is a number of heated or ablated large dust particles, then the questions addressed here are: how far will the ablated dust material penetrate and what effect will this have on the edge of the pedestal in relevant JET D and in a high fusion yield D-T discharges. The methodology is based on the use of an upgraded version of the ballistic code DUSTTRACK and a new code PELLYTIX for dust ablation modelling. Considering a reasonable amount of dust released from the tiles, the analysis shows that the ablation-penetration depth is visible in the density pro les modification, but not disastrous for tokamak operation in high regimes.