Modelling of the pellet cloud evolution and mass deposition with an account of del B induced drift

摘要

Modelling of the pellet ablation cloud evolution including the del B induced drift motion is performed. The model includes cloud heating, expansion and ionization, acceleration in the low-field side (LFS) direction, Alfven conductivity of the background plasma, compensation of del B currents in different parts of the cloud during its propagation along the magnetic field, cooling of the background plasma and simulation of the pellet ablation rate in a self-consistent manner. The time evolution of cloud density and temperature profiles and the mass deposition after the pellet injection are calculated. The LFS and high-field side injection scenarios with plasma and pellet parameters typical for the ASDEX-Upgrade tokamak are compared. An effect of pre-cooling on the pellet penetration depth is studied. The calculated size of the neutral part of the cloud, the characteristic values of cloud density and temperature far from the pellet and the fuelling efficiency (for LFS pellets) are in reasonable agreement with those observed in experiments on the ASDEX-Upgrade.