Surface microstructure and composition of plasma facing components from the
TEXTOR tokamak are described. Surfaces of such components are drastically
modified by the impact of plasma ions. This interaction results in the form
ation of thick co-deposited/co-implanted layers containing a mixture of hyd
rogen isotopes and plasma impurity species. The emphasis is on the characte
risation of changes occurring on the graphite surface exposed for a few hou
rs to a hot deuterium plasma and, afterwards, following the exposure either
to air or annealing in vacuum at elevated temperatures. The investigation
carried out by means of electron microscopy, energy dispersive X-ray spectr
oscopy, ion beam analysis methods and laser profilometry gives evidence on
the conditions under which the deuterium is released due to the oxidation o
r desorption from the plasma eroded surfaces. It is also demonstrated that
the oxygen-assisted removal of deuterium at 300 degrees C has rather small
impact on the decomposition of thick co-deposits. (C) 1999 Elsevier Science
S.A. All rights reserved.