Deuterium interaction with silicon-graphite materials exposed to the tokamak plasma

Silicon-containing composites are considered as plasma facing materials in controlled fusion devices. Comparative studies of deuterium interaction with carbon based substrates were performed for graphite-silicon mixtures (5-50 wt% of Si), carbon fibres and isotropic graphite. Both virgin and deuterium treated surfaces were characterized by means of several surface sensitive techniques. The substrates were exposed to the deuterium plasma in the TEXTOR tokamak, in a magnetron or in a hollow cathode. The uptake, retention and release of deuterium were investigated. Migration of deuterium from the plasma deposited layer to the bulk of the substrates was found for the graphite-silicon mixtures. The structure of the deuterium-containing deposits was studied using atomic force microscopy. The initial stage of bubble formation was observed on the surfaces exposed to the tokamak plasma. (Author)