DETERMINATION OF JET SCRAPE-OFF LAYER TRANSPORT-COEFFICIENTS USING AN INTERPRETATIVE ONION-SKIN PLASMA MODEL

Currently there is much interest in the application of sophisticated 2D codes to model the scrape-off layer (SOL) plasma in divertor tokamaks. These models generate the plasma solution at the divertor target starting from boundary conditions defined on a closed flux surface near the separatrix. An alternative approach, used within the DIVIMP code [1], is to anchor the boundary conditions at the divertor target using experimental Langmuir probe measurements and then solve the 1D fluid equations along each flux tube in the SOL generating an ''onion-skin'' model. Interaction of the plasma with recycled neutrals is included by coupling to a 2D neutral transport code. Such a model has been applied to analyse the SOL plasma transport in JET divertor discharges from the previous experimental campaign. Following the approach of Shimizu et al. [2], the radial variation of the anomalous cross-field transport coefficients (D-perpendicular to, chi(perpendicular to)) are evaluated over a range of discharges and compared with results from a 2D predictive code.