Berlin 2001 – scientific programme

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P: Plasmaphysik

P 8: Magnetic Confinement and Plasma Technology (Poster Session)

P 8.6: Poster

Monday, April 2, 2001, 12:30–15:00, AT2

Divertor Retention and Penetration Probabilities for Tungsten at ASDEX Upgrade — •Alexander Geier, Rudolf Neu, Hans Maier, Karl Krieger, and ASDEX Upgrade Team — Assoziation

The applicability of tungsten as plasma facing material was investigated at ASDEX Upgrade by coating of tiles at the lower central column and in the divertor. Thereby no severe adverse effects on the plasma performance could be observed. Prior to an extrapolation to ITER, however, more physical understanding is necessary. Essential parameters for the central tungsten concentration are the divertor retention potential for tungsten and its penetration probability p through the Scrape-Off-Layer into the region of closed fieldlines. At ASDEX Upgrade this probability was measured by means of the Laser-Blow-Off system comparing injecton from the high-field and th low-field side. Using the sublimation probe [1], the value for p could be compared between different poloidal positions. The divertor retention potential could be measured using the sublimation probe in the divertor along with a deposition probe in the main chamber. Therefore, however, a significant increase of the detection sensitivity of the deposition probe was necessary. Additionally, the spectroscopic detection limit for tungsen in the main plasma could be reduced using a focussing X-Ray spectrometer.

[1] A. Geier et al., Rev. Sci. Instr. 70, (1), 1999