Berlin 2005 – wissenschaftliches Programm
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P: Plasmaphysik
P 24: Plasma-Wand Wechselwirkung 3
P 24.3: Vortrag
Mittwoch, 9. März 2005, 11:30–11:45, HU 3038
Operation with a Tungsten First Wall - Studies at ASDEX Upgrade — •T. Pütterich1, R. Neu1, R. Dux1, A. Kallenbach1, C.F. Maggi1, J.C. Fuchs1, O. Gruber1, A. Herrmann1, P. Lang1, H. Meister1, M. O’Mullane2, I. Radivojevic1, V. Rohde1, A. Whiteford2, and ASDEX Upgrade Team1 — 1MPI für Plasmaphysik, EURATOM-Association, Garching, GERMANY — 2Department of Physics, University of Strathclyde, Glasgow, UK
Carbon as a plasma facing component (PFC) will not be an option for a fusion reactor, as it would exhibit unacceptable strong erosion. Additionally, the codeposition of tritium in a-CH layers is an unresolved safety issue. Both led to the reconsideration of high-Z materials as PFCs. To investigate the feasibility of high-Z PFCs in a fusion device, an increasing area of the first wall in ASDEX Upgrade was coated with W since 1999, reaching 65 % (24.8 m2) in the 2003/04 campaign. Concomitantly, the W-diagnostic was improved by new atomic data, calculated with the Cowan-code. Whereas the W-concentration, which stayed below critical levels, has increased moderately with increasing W-surfaces, the C-concentration has hardly been affected and is still 1 –2 %. Investigations on different source locations of tungsten will be presented that give insight in erosion mechanisms and the importance of impurity sources. Central wave heating has been shown to be efficient for avoiding impurity accumulation, also for improved H-modes, i.e. special high performance discharges. Finally, an integrated, ITER-relevant scenario is introduced, which combines recipes for operation with W-PFCs, including edge cooling by argon puffing and ELM-pacemaking for impurity control.