Plasma induced erosion and redeposition at the vessel walls has been measured by surface layer analysis of a carbon probe with evaporated markers before and after exposure in the boundary plasma of the TEXTOR tokamak. The results are compared with those calculated with the computer simulation program ERO. The erosion is dominated by carbon and oxygen impurity fluxes in the boundary plasma. Carbon is deposited on the marker surfaces and has to be resputtered for the marker material to be sputtered. Mo atoms sputtered from the marker are found to be redeposited in the slit of the probe. The redeposition pattern can be explained by direct deposition of sputtered Mo neutrals.
Impurity plume experiments in the edge plasma of the Alcator C-Mod tokamak