A MODEL OF HYDROGEN IMPACT-INDUCED CHEMICAL EROSION OF CARBON-BASED ON ELEMENTARY REACTION STEPS

Based on the elementary reaction steps for chemical erosion of carbon by hydrogen a model is developed which allows to calculate the amount of carbon erosion at a hydrogenated carbon surface under the impact of hydrogen ions and neutrals. Hydrogen ion and neutral flux energy dist ributions prevailing at target plates in the ASDEX upgrade experiment are chosen in the present calculation. The range of hydrogen particles in the target plates is calculated using TRIDYN code. Based upon the TRIDYN results the extent of the erosion reaction as a function of dep th is estimated. The results show that both, target temperature and im pinging particle flux energy distribution, determine the hydrogen flux density dependent erosion yield and the location of the erosion below the surface.