Numerical modelling of high density JET divertor plasma with the SOLPS4.2 (B2-EIRENE) code

SOLPS 4.2 is a version of the B2-EIRENE code which is currently used for predictive modelling studies of the ITER divertor design. This paper presents the results of calculations made for a series of high density shots at JET employing exactly the same physics model as that used for the ITER application. A complete as possible comparison with experimental data has been performed and relatively good agreement (within a factor 2) has been found for the outer divertor (with the exception of the temperature profile). At the inner divertor agreement is worse, particularly at the highest density. The sensitivity of the numerical solution to refinements in the recycling model has been explored. An important finding is that an improved molecular kinetics model (including elastic collisions between molecules and ions) can significantly affect the results. The influence of non-linear effects (neutral-neutral collisions and line radiation opacity) is found to be weak in the discharges studied even at the highest density, in contrast to ITER simulations with the same model.