Full-tungsten plasma edge simulations with SOLPS

We review different approaches available for plasma edge modeling when including tungsten impurities. We focus on the bundled charged states method, and perform a sensitivity study, against a full fluid treatment, for a benchmark ASDEX-Upgrade case. We consider several indicators, such as net wall erosion/deposition rates and plasma power balance. In general, differences are modest, but material migration rates are slightly underestimated with bundles versus the full treatment. At the same time, radiated power and heat flux to the divertors can vary significantly from one bundling scheme to the other. It therefore appears that bundling of several ionic stages into single atomic "species", while providing a marked code speed-up (by reducing the number of equations by up to a factor 4), must be used with care when making divertor behavior predictions. (C) 2010 Elsevier B.V. All rights reserved.