Observation of non-uniform erosion and deposition phenomena on graphite after plasma exposure

The modifications of fine grain isotropic graphite surfaces after plasma ex posure have been investigated using surface analysis techniques with high s patial resolution in area and depth. The samples are graphite target tiles of ASDEX-Upgrade and coated graphite collector samples exposed for special erosion/deposition experiments in the divertor plasma of ASDEX-Upgrade or i n the scrape-off plasma of TEXTOR-94. In addition, a graphite sample was ex posed to a low temperature, clean deuterium plasma to study the modificatio ns of the surface morphology during plasma exposure. The results give clear indications of non-uniform erosion and deposition processes. The change of the surface morphology during these processes is discussed.