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The hydrogen desorption and air oxidation of amorphous deuterated carbon (a-C:D) films deposited on Si are investigated. The results are compared with a hydrogenated carbon layer deposited on a silicon collector sample mounted on the wall of tokamak ASDEX Upgrade during 6 months' plasma operation. The a-C:D films, deposited on a silicon substrate by the RF glow-discharge method, are exposed to air at room temperature and between 500 and 800 K. The total amounts and depth profiles of both deuterium and carbon are measured by elastic recoil detection (ERD) and proton enhanced scattering (PES). It is found that the surface deuterium loss is accompanied by oxygen uptake and hydrogen isotope exchange in the film until deuterium is completely released. Further annealing leads to the removal of the whole carbon layer. In accordance with previous oxygen implantation studies the erosion is modeled to be due to the chemical reaction of carbon and deuterium with oxygen from air. The removal of the codeposited layer from the ASDEX-Upgrade sample proceeds much faster than that found for a-C:D films under identical treatment conditions. The removal rate strongly depends on film structure.

Additional information

Authors: WANG W, Shanghai Institute of Nuclear Research, Academia Sinica (CN);JACOB W, Max-Planck-Institut für Plasmaphysik, Garching bei München (DE);ROTH J, Max-Planck-Institut für Plasmaphysik, Garching bei München (DE)
Bibliographic Reference: Article: Journal of Nuclear Materials, Vol. 245 (1997) No. 1, pp. 66-71
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