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15th International Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI 15), Gifu, 2002-05-26 to 2002-05-31
Abstract:
In ASDEX Upgrade, tungsten is employed as plasma facing material at the central column of the
plasma main chamber. The campaign averaged tungsten erosion flux was determined by measuring
the difference of the W-layer thickness before and after experimental campaigns using ion beam
analysis methods. The lateral variations of the observed tungsten erosion flux reflects the pattern of
magnetic field lines intersecting the respective plasma facing surfaces. Long term migration and
redeposition of eroded tungsten were investigated by ion beam analysis of deposited tungsten on
wall samples from main chamber and divertor. The obtained results, as well as the spectroscopically
observed low tungsten plasma penetration probability, indicate that a major fraction of the eroded
tungsten migrates predominantly through direct transport channels in the outer plasma scrape-off
layer without entering the confined plasma.
