Study of gross and net erosion in the ASDEX upgrade divertor

Erosion of carbon and tungsten in the divertor of ASDEX Upgrade was investigated by surface analysis of target tile probes. The probes were exposed in the divertor using a manipulator system. Erosion of carbon was measured by graphite probes covered with a 150 nm layer of (13) C isotope to distinguish from the intrinsic carbon content. Tungsten erosion was measured by similar probes with 1-20 nm tungsten markers evaporated on the surface. From the measured erosion, sputtering yields were determined using plasma parameters at the target plates obtained from flush mounted Langmuir probes.