SOLPS simulations for alternative divertor configurations in the future upper divertor in ASDEX Upgrade

High heat loads on the plasma facing components of tokamak divertors impose serious constraints on the achievable performance of future fusion reactors. ASDEX Upgrade (AUG) recently decided the upgrade of its upper divertor to study alternative divertor configurations (ADCs) which are currently discussed as a possible solution for the power exhaust problem. Validated by recent AUG experiments in upper single null (SN) configuration, the SOLPS code was applied to extrapolate the performance of the X-divertor and snowflake configurations in the future upper divertor. With the same heating, fueling and impurity seeding, as well as similar parameter profiles at the outer mid-plane, the simulations predict a much lower target power load in ADCs than that in SN configuration. This is explained by a larger radiation volume and an enhanced volumetric recombination rate in such ADCs. Simulations with drifts show a modified cross-field transport and the activation of a secondary strike point.