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T. Lunt, Y. Feng, K. Krieger, R. Neu, H. Müller, E. Wolfrum, M. Willensdorfer, M. Wischmeier, . ASDEX Upgrade Team:
"EMC3-Eirene simulations of the spatial dependence of the tungsten divertor retention in ASDEX Upgrade";
Plasma Phys. Control. Fusion, 53 (2011), 1250101 - 12501011.

The Edge Monte Carlo 3D (EMC3)-Eirene code package is applied to simulate
the deuterium plasma and neutral particle as well as the tungsten impurity
transport in ASDEX Upgrade. Good agreement is found for the deuterium
bulk plasma for an L-mode discharge both in the upstream and downstream
profiles. The tungsten concentration in the core is computed for a point source
placed at different positions around the outer strike point. Comparing the
mean impurity residence time for divertor and main chamber sources yields
the divertor retention factor R, which shows a very strong dependence on the
location of the source relative to the strike point and also on the discharge
parameters. While the tungsten transport is strongly suppressed directly at the
strike point, it becomes much more efficient in the region 20-100mm away
from it in the far scrape-off layer.