In-Situ Observation of Sputtered Particles for Carbon Implanted Tungsten During Energetic Hydrogen Isotope Ion Implantation

The effect of carbon implantation for the dynamic recycling of deuterium, which demonstrates tritium recycling, including retention and sputtering, was investigated using in-situ sputtered particle measurements. The C⁺ implanted W, WC and HOPG were prepared and dynamic sputtered particles were measured during H₂ ⁺ irradiation. It was found that the major hydrocarbon species for C⁺ implanted tungsten was found to be CH₃, although those for WC and HOPG were CH₄. The chemical state of hydrocarbon is controlled by the H concentration in a W-C mixed layer. The amount of C-H bond and the retention of H trapped by carbon atom should control the chemical form of hydrocarbon sputtered by H₂⁺ irradiation and the desorption of CH₃ and CH₂ was due to chemical sputtering, although that for CH was physical sputtering. The activation energy for CH₃ desorption was estimated to be 0.4 eV, corresponding to the trapping process of hydrogen by carbon through the diffusion in W. It was concluded that the chemical states of hydrocarbon sputtered by H₂⁺ irradiation for W was determined by the amount of C-H bond on the W surface.