Erosion of tungsten and steel in the main chamber of ASDEX Upgrade

We have investigated net erosion and deposition of W and P92 steel in ASDEX Upgrade during its full-W operational phase. The outer divertor and the outer midplane are the strongest net erosion region for W, with rates up to 0.12 nm/s and 0.05 nm/s, respectively. The eroded W is transported via the scrape-off layer plasma and predominantly deposited in the upper (20-30%) and inner divertors (40-60%). The inner midplane does not contribute significantly to the erosion-deposition balance such that the remaining W is deposited in shadowed areas of the tokamak. Steel is eroded 3-10 times faster than W but could be used at the top and inner parts of the main chamber where the erosion rate is ∼0.01 nm/s.