Gas release from low-Z materials under hydrogen bombardment

Much interest has been expressed recently in materials of low atomic number for use inside the containment vessel of large plasma physics experiments. Results are presented here for D+ ion trapping and thermal desorption spectrometry from carbon and silicon carbide. Deuterium re-emission is observed continuously during bombardments which have been conducted both at room and elevated target temperatures. Thermal release spectra following D+ irradiations of carbon show a single narrow peak, characteristic of a single-step process which correlates with the activation energy required to break an H-C bond. Silicon carbide gives rise to a triple peak structure in the gas release spectra. Following low doses (<=1016 ions/cm2), the highest temperature and major peak occurs at 11500C, and is coincident with the single peak observed in carbon spectra. (author)