Session RP1 - Poster Session VIII.
POSTER session, Thursday afternoon, October 30
Fran Hill Southeast Exhibit Hall, ACC
Plasma impurity content depends upon impurity sources, fuelling efficiency, and confinement. In JET, carbon is the primary impurity, and its fuelling efficiency has been studied using methane gas injection. In this poster, EDGE2D modelling of the JET experiments and similar AUG experiments are extended to ITER. For carbon injected at the mid-plane, screening depends upon: the SOL temperature, the carbon ionisation depth, the thermal force near the divertor entrance, the parallel distance to the divertor, and the SOL flux expansion. For carbon injected at the strike points, the carbon screening depends upon the carbon ionised in the region where the thermal force is strong. In JET, carbon, originating inside the divertor, had typically 5% chance of reaching the main chamber SOL, but from the main chamber SOL had about 10% chance of contaminating the core plasma. By contrast, carbon originating in the main chamber, was typically 95% ionised inside the main chamber SOL but had only 4 to 10% chance of contaminating the core. Since the ITER SOL will be hotter, and the ITER divertor will be larger than JET, the calculated carbon screening is much better.