COMPARISON BETWEEN MEASURED SCRAPE-OFF LAYER PLASMA PARAMETERS AND 2DMODEL-CALCULATIONS FOR JET X-POINT DISCHARGES

Modelling with the EDGE2D/U-NIMBUS code of the measured scrape-off lay er plasma parameters for JET divertor discharges is presented. Model r esults agree with the experiment if very small values (less than or si milar to 0.1 m(2)/s in H-modes and low power L-modes) for the anomalou s particle transport diffusion coefficient in the SOL are used. While the assumption of the power flow out of the main plasma being carried equally by the electrons and the ions describes satisfactorily the glo bal power balance for Ohmic and L-mode discharges, more power flowing out through the ion channel is consistent with the power balance in ho t ion H-modes. Some sensitivity studies of the code results on the mod elling hypothesis are discussed.