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

The thermal stability of 200nm 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 21days) 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 514nm photon absorption evolution due to the thermal treatment of the layer. The effects of isotopic substitution have also been investigated.