Thermal stability and long term hydrogen/deuterium release from soft to hard amorphous carbon layers analyzed using in-situ Raman spectroscopy. Comparison with Tore Supra deposits

• Thermal stability of amorphous hydrogenated/deuterated layers has been studied.
• In situ Raman spectroscopy linear ramp and long term isotherms have been recorded.
• The effects of isotopic substitution have been investigated.
• We confirm that the layers containing the more H or D are the less thermally stable.
• 514 nm photon absorption evolves as the G band shifts.

The thermal stability of 200 nm thick plasma enhanced chemical vapor deposited a-C:H and a-C:D layers ranging from soft to hard layers has been studied and compared to that of deposits collected on the Tore Supra tokamak plasma facing components by means of in-situ Raman spectroscopy. Linear ramp heating and long term isotherms (from several minutes to 21 days) have been performed and correlations between spectrometric parameters have been found. The information obtained on the sp2 clustering has been investigated by comparing the G band shift and the 514 nm photon absorption evolution due to the thermal treatment of the layer. The effects of isotopic substitution have also been investigated.