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P: Plasmaphysik

P 1: Plasma Wall Interaction

P 1.3: Vortrag

Montag, 17. März 2003, 16:25–16:45, FO1

Short range carbon transport near plasma wetted surfaces in TEXTOR — •Peter Wienhold¹, Andreas Kirschner¹, Volker Philipps¹, and Marek Rubel² — ¹Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, 52425 Jülich — ²Alfven Laboratory, KTH, S-10044 Stockholm, Sweden

Carbon erosion and transport remains a major concern in future fusion devices because tritium containing flakes can be formed in areas less affected by the plasma. In TEXTOR, the major carbon source is the graphite belt limiter (3.4m²) where up to 22 grams of carbon are eroded per plasma hour from the surface. This carbon is mainly transported to locations inside the torus or to the pump ducts, but part of it (10g/h) is directly re-deposited on the plasma wetted limiter surface itself. This is due to a short range transport of the chemically eroded species to zones of grazing incident toroidal field lines where the erosion efficiency of the deuterium ion flux is reduced. This causes carbon accumulates and the formation of flakes up to 10 microns thickness. The stratification of the flakes reveals a continuous transport and deposition day by day over long periods of time. The observations can be understood quantitatively by means of estimates with the ERO-TEXTOR code taking into account the carbon impurity fluxes and the local plasma conditions