Synergistic methane formation kinetics for hydrogen impact on carbon

Abstract

A physical/chemical model is presented for the reaction kinetics for methane formation from carbon, due to bombardment by energetic (∼100’s eV) H+ ions and thermal (∼1 eV) H0 atoms. While the model was developed for H+ and H0, it can be readily applied to nonhydrogenic energetic particles (ions or atoms, e.g., Ar+, He+, He) in combination with thermal (∼1 eV) hydrogen (again ions or atoms) impacting on carbon. Both collisional (in the case of the energetic particles) and chemical reaction processes are included. Special cases of sub-eV H0 alone, energetic H+ alone, and combined H0 plus H+ were considered and fitted to experimental data. Generally good agreement was found between theoretical predictions and experimental results over the experimental flux and H+ energy ranges studied (H0 flux: 6×1014–7×1015 H0/cm2 s, H+ flux: 6×1012–5×1015 H+/cm2 s, H+ energy: 300 eV/H+ and 1 keV/H+).