Abstract
Carbon erosion at the outboard divertor in ASDEX Upgrade has been investigated using the emission spectroscopy technique. The methane molecular influx was calibrated by simultaneous CD4 puffing. In deuterium H-mode discharges a decrease of D/XBCD←CD4 with increasing ion flux (decreasing temperature) is found at fluxes in the range 0.5–2×1022m−2s−1 and no dependence for higher fluxes. The corresponding obtained yields show a negative power law flux dependence with exponent γ=−0.46. To investigate the combined effect of re-deposition, re-erosion and local transport, known quantities of 13CH4 were puffed at the end of the 2002/2003 experimental campaign. The amount of 13C locally redeposited has been measured by nuclear reaction analysis (NRA). The results show a strongly localised re-deposition near the puff location, with a downstream tail and a moderate downward drift with respect to the magnetic field line direction.
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