Chemical interaction of hydrogen with graphite in regard of hydrogen recycling and chemical erosion of fusion reactor first wall material

A simple model is presented here to evaluate the desorption rate of hydrocarbons from graphite that was preirradiated by hydrogen ions. The model is applied to the experimental results of the thermal desorption studies obtained by the present authors. The model does not include any other physical parameters than those used in the current hydrogen release models, thus providing an opportunity to test these models in the light of hydrocarbon formation where various chemical reactions are considered to be taking place. The analysis revealed that the parameters thus determined differ considerably from those employed in those hydrogen release models. Although the elemental processes assumed in the models are yet to be clarified, the present results seem to imply that further improvement of the model is necessary.