Quantitative AMS depth profiling of the hydrogen isotopes collected in graphite divertor and wall tiles of the tokamak ASDEX-Upgrade

The accelerator mass spectrometry (AMS) facility at the 3 MV Tandetron in Rossendorf has been applied for quantitative depth profiling of deuterium and tritium in samples cut from graphite protection tiles at the vessel walls of the fusion experiment ASDEX-Upgrade at the Max-Planck-Institut fur Plasmaphysik in Garching. The tritium originates from D(d,p)T fusion reactions in the plasma and it is implanted in the vessel walls together with deuterium atoms and ions from the plasma. The T concentrations in the surface layers down to the analyzing depth of about 25 mu m are in the range of 10(11) to 5 x 10(15) T-atoms/cm(3) corresponding to a tritium retention of 3 x 10(10) to 3.5 x 10(12) T-atoms/cm(2). The much higher deuterium concentrations in the samples were simultaneously measured by calibrated conventional SIMS. In the surface layers down to the analyzing depth of about 25 mu m the deuterium concentrations are between 3 x 10(18) and 8 x 10(21) atoms/cm(3), corresponding to a deuterium retention of 2.5 x 10(16) to 2.5 x 10(18) atoms/cm(2) The estimated total amount of tritium in the vessel walls is of the same order of magnitude as the total number of neutrons produced in D(d,n)He-3 reactions. (C) 1997 Elsevier Science B.V.