Strong Asymmetries in Impurity Distributions of JET Plasmas

摘要

1. Strong in-out asymmetries are observed in the soft X-ray emission from JET hot-ion H-mode plasmas. The peak is observed on the outboard side.rn2. The key feature of the asymmetry can be explained by the effect of the centrifugal force on metal impurity ions in these rapidly rotating plasmas, where rotational velocities 3 times the thermal velocity are prevalent.rn3. A simple model has been developed which produces quantitative agreement with data from a discharge where laser ablation of nickel into the plasma was performed.rn4. The radial distribution of impurity ions with a stationary peak at R~3.6m and a secondary peak developing later on-axis is less well understood. (The outboard peak has in one case been observed to move out to a larger radius following a sawtooth, for example.)rn5. Models are being developed to see if these results can provide a greater insight into particle diffusion profiles.