  Fine-grain graphite targets have been exposed to ITER divertor relevant
plasmas in Pilot-PSI to address material migration issues in fusion devices.
Optical emission spectroscopy and mass loss measurements have been employed to
quantify gross chemical erosion and net erosion yields, respectively. Effects
of the ion impact energy and target geometry on carbon erosion yields have been
studied. It is concluded that temporal evolution of gross chemical erosion is
strongly connected with changes in morphology of plasma exposed surfaces. The
net carbon erosion yield is increased when the targets are partly covered by
insulating boron-nitride rings.
