High temperature irradiation damage of carbon materials studies by laser Raman spectroscopy

In order to characterize carbon materials exposed to hydrogen, deuterium and helium plasmas at elevated temperature, we have applied laser Raman spectroscopy. We have found that the exposure to high dense plasma at an elevated temperature, 700–1200 K, does not amorphize the carbon materials. The specimen exposed to the plasma keeps two-dimensional structure orders, though their grain sizes or crystallites are fragmented into very fine ones. Heavier ions irradiation (He) results in more fragmentation than lighter ions (H). Hence the displacement played more important role and the chemical effect of hydrogen which is not appreciable because of spontaneous release of hydrogen at high temperatures. This indicates that hydrogen retention in carbon materials can be significantly reduced at elevated temperature operation. Furthermore the Raman spectroscopy could be used for in situ analysis of carbon based plasma facing materials.