Hydrogen isotope depth profiling in carbon samples from the erosion dominated inner vessel walls of JET

In order to investigate the hydrogen isotope accumulation at the erosion do minated inner walls of fusion experiments, several small carbon samples hav e been mounted in the inner wall tiles of the torus of the JET Joint Undert aking. After about 2.5 years of JET operation, including the extended D/T p hase and the D/D cleaning phase, the samples have been removed and analysed by RES, ERDA and AMS. In the near surface region only small T concentratio ns are measured. A much larger T concentration is found at depths between a bout 1 and 2 mum. This may originate from energetic (similar to1 MeV)T whic h is produced during the D/D discharges and implanted to large depth. The l ower energy (keV) T which is implanted during the D/T discharges became eff ectively removed from the inner wall, by isotope exchange with implanted D or H and/or by erosion of the wall. The total amount of T within a depth of about 2 mum was found to be about 1-3 x 10(13) T/cm(2), while in a surface layer of about 0.5 mum about 1-3 x 10(12) T/cm(2), about 2-4 x 10(16) D/cm (2) and about 4-9 x 10(16) H/cm(2) were measured. (C) 2001 Elsevier Science B.V. All rights reserved.