Simulation of pellet ablation in DIII-D tokamak

We investigated by numerical simulations the effect of various physical parameters on the pellet ablation rate in a tokamak. In particular, we did benchmark simulations against exprimental data from DIII-D tokamak pellet launches. As a model for the tumbling pellet, the anisotropic heating of pellet was averaged over the pellet surface so that the pellet remains spherical as it ablates. The rotation of the pellet due to the distribution of electrostatic potential was included in the simulations. DIII-D plasma temperature profile was used, while the plasma density was assumed to have a linear ramp in the pedestal region. The pellet lifetime and density profiles reproduced by simulations have been compared to the experimental measurements. The mechanisms for the striation in the ablation cloud have also been studied numerically.