Hannover 2010 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 21: Poster: Plasma-Wall Interaction
P 21.4: Poster
Montag, 8. März 2010, 16:00–18:00, Lichthof
W behaviour in N2 seeded discharges in ASDEX Upgrade — •R. Neu1, R. Dux1, A. Janzer1, A. Kalllenbach1, R. McDermott1, H.W. Müller1, S. Potzel1, T. Pütterich1, M. Sertoli1, G. van Rooij2, and ASDEX Upgrade Team1 — 1MPI für Plasmaphysik, EURATOM Association, D 85748 Garching — 2FOM-Institute for Plasma Physics Rijnhuizen, Assoc. Euratom-FOM, Trilateral Euregio Cluster, 3430 BE, Nieuwegein, NL
Radiative cooling is an important tool to lower the power loads to plasma facing components. Amongst the different species used, nitrogen has been shown to provide the best cooling effect in ASDEX Upgrade discharges, while maintaining or even improving the confinement. Depending on the background plasma density and the divertor temperature a reduction or increase of the W sputtering yield compared to the unseeded phases was observed. In discharges with very high density, divertor plasma temperatures below 5 eV can be achieved leading to a complete suppression of the W sputtering. The W influx is a necessary prerequisite for the central W concentration (cW), nevertheless it has been shown that cW is mainly governed by transport. Although the energy confinement increases often in N2 seeded discharges no strong increase in cW is observed and there are no signs of central density peaking and W accumulation. Moreover the sustained regular ELM activity prevents a strong inward transport of W across the pedestal region.