Mass deposition after pellet injection into a tokamak

Abstract

The shift of the ionized plasma cloud, which is created in the process of pellet ablation, in the low field side (LFS) direction is calculated. It is demonstrated that the shift is determined, on the one hand, by the acceleration of a cloud in the LFS direction, and, on the other hand, by the reduction of the cloud polarization. The latter is caused by the generation of Alfven waves and compensation of the ∇B drifts in different parts of the cloud propagating along the magnetic field. Dissipative mechanisms of polarization reduction turned out to be less significant. An expression for the cloud displacement may be used to specify the initial density profile for simulation using one-dimensional transport codes. The calculated shift of the plasma cloud is consistent with the observations in ASDEX-Upgrade and DIII-D.