Rapid Inward Impurity Transport During Impurity Pellet Injection on the DIII-D Tokamak

Neon killer pellets are injected into the DIII-D tokamak plasma in order to radiatively quench the plasma{close_quote}s stored energy and mitigate disruption effects. Inward radial transport on the time scale of the pellet ablation ({le}1 ms) results in central deposition of the neon inside the ablation penetration radius of the pellet, causing effective radiative energy dissipation. This result is in contrast to the radially outward deposition measured for fueling (hydrogenic) pellets. The observed magnitudes of magnetic fluctuations ({delta}B/B{approximately}0.2{percent}) are shown to be capable of causing the radial transport. {copyright} {ital 1998} {ital The American Physical Society }