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Atomic Hydrogen Interaction with Carbon

O. Auciello, A. A. Haasz, P. C. Stangeby

Fusion Science and Technology / Volume 6 / Number 2P2 / September 1984 / Pages 411-413

Technical Paper / Selected papers from the Ninth International Vacuum Congress and the Fifth International Conference on Solid Surfaces (Madrid, Spain, September 26-October 1, 1983) / dx.doi.org/10.13182/FST84-A23214

Methane production yields due to sub-eV H° impact on carbon are in the 10−3 – 10−4 CH4/H° range, i.e., about two orders of magnitude less than CH4/H+ yields for 0.1 – 100 keV H+ ions. Two macroscopic states of “reactivity” were identified for carbon: an “activated” state characterized by a CH4 yield vs. sample temperature curve with a maximum at 700–850K, and a “deactivated” state characterized by a monotonically decreasing yield as a function of temperature. Regarding the retention of sub-eV H° and D° in carbon, our results differ from previously published results. We have observed lower levels of trapped H° (∼1015 H°/cm2), with an apparent trend for saturation, at incident fluences of >2×1019 H°/cm2. Strong synergistic effects have been reported for combined sub-eV H°/5 keV Ar+ impact, while it appears that “insignificant” synergism exists for combined sub-eV H°/e impact.