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

Abstract

Abstract A modelling analysis is performed on JET D and DT discharges, where W dust influx across the separatrix, in the pedestal edge region may affect 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 profiles modification, but not disastrous for tokamak operation in high regimes.