Bochum 2015 – scientific programme

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P: Fachverband Plasmaphysik

P 3: Plasma Wall Interactions

P 3.1: Invited Talk

Monday, March 2, 2015, 14:00–14:30, HZO 50

The importance of impurity migration in present and future fusion experiments — •Klaus Schmid, Gerd Meisl, and Karl Krieger — Max-Planck Institut für Plasmaphysik, Garching Germany

The plasma in the scrape off layer of magnetic confinement fusion plasmas is defined by the power and particle flux from the confined core plasma and by the recycling of hydrogen species and generation of impurities at the location where its open field lines intersect with plasma-facing wall components. The erosion of elements from these first wall elements is determined by physical or chemical sputtering by the incident particle flux or by sublimation at high temperatures. All of these processes also depend on the surface state (e.g. composition) which varies as material is eroded and subsequently re-deposited forming mixed-material layers.

Thus to describe the evolution of the first wall a coupled, self-consistent description of the particle sources at the surface and the migration of impurities in the plasma is required. To that end the WallDYN code was developed.

In this presentation the migration of two elements, Beryllium (Be) and Nitrogen (N) , with rather different deposition properties will be compared by applying WallDYN to interpret experimental results from ASEDX-Upgrade and JET in ITER like Wall (JET-ILW) configuration. Finally based on this model benchmark an extrapolation of the expected Be co-eposition and N accumulation in ITER will be presented.