Assessment of scrape-off layer simulations with drifts against L-mode experiments in ASDEX upgrade and JET

Numerical simulations of divertor power and particle fluxes in L-mode exhaust scenarios are presented, in comparison to experiments in the full-metal devices ASDEX Upgrade and JET. The simulations are performed using the plasma fluid – Monte Carlo neutrals code package SOLPS5.0, with cross-field drift terms activated. We present a validation of the simulation results against dedicated benchmark experiments with and without nitrogen seeding and discuss the effect of drifts on the modelled divertor asymmetries. At low power dissipation levels, asymmetric divertor conditions are obtained in the simulations as a result of E × B drifts, and the modelled volume distributions of particles and energy are largely confirmed by the multiple experimental measurements in both devices. In high-recycling conditions close to the roll-over of the ion fluxes at the target plates, the measured ion fluxes exceed the simulated levels by up to a factor of 6. The discrepancy between the modelled and measured target ion flux evolution is stronger when the divertor conditions are controlled by increasing the deuterium fuelling, in comparison to increasing the impurity-seeding level at constant line-averaged density.