Deuterium concentration in deposited carbon layers in Tore Supra

Deposited carbon layers observed in the tokamak Tore Supra have been sampled in order to quantify their deuterium content using D(3He, p)4He nuclear reaction analysis. The results show two trends: the D/C ratio in wetted deposited carbon layers is less than 1% and the D concentration depth profile decreases rapidly from the first micrometers of the plasma facing sub-surface to the rear surface, while the D/C ratio in shadowed deposited carbon layers reaches about 10% and shows a more constant profile along the probed depth. Using the information about D concentrations and of the maximum thickness of the different samples and with the estimated deposited areas, an estimated D inventory is found to be about 1 × 1023D, which is too low to account for the D retention expected for a whole long plasma discharge campaign.