Effect of B×∇B Direction on SOL Energy Transport in JET
The toroidal field and plasma current were reversed in recent JET experiments. Over 100 discharges were obtained, some with good forward field references. Target power deposition was measured using divertor thermocouples. The poloidal power flow in the SOL were found to depend on the B¥B direction; radiation asymmetries played a minor role in the power balance. The direction, magnitude and scaling of this poloidal power flow can be explained by classical drift-related heat fluxes (E¥B and/or B¥T) whose relative contribution scales rqs/ lTs. Radial transport is largely independent of the B¥B direction, which together with previous experiments rules in favour of classical ion conduction (no B¥B dependence) as the dominant SOL radial transport mechanism, and against the ion orbit loss process (strong B¥B dependence). These results were confirmed by detailed EDGE2D and ASCOT simulations of relevant JET plasmas.