Fusion Science and Technology / Volume 41 / Number 3P2 / May 2002 / Pages 902-906
Material Interaction and Permeation / Proceedings of the Sixth International Conference on Tritium Science and Technology Tsukuba, Japan November 12-16, 2001
Isotropic graphite of ETP-10 was exposed to a deuterium rf-plasma at room temperature and depth profiles of deuterium near the plasma-facing surface were observed by a nuclear reaction analysis. The depth profile consisted of two parts, which were a peak at the surface and a gradual slope downward to the depths. The surface density of deuterium estimated from the peak area was saturated with longer time and hardly decreased after the exposure. This was explained by that the incident deuterium atoms from the plasma were absorbed on deuterium-free sites and absorbed atoms were not desorbed. The deuterium concentration in the bulk increased nearly in proportion to the square root of time and gradually decreased after the plasma exposure. This was explained by a simple diffusion model and an apparent diffusion coefficient was found to be 2x10−18 m2s−1 from the depth profile.