An overview of nuclear micro-beam analysis of surface and bulk fuel retention in carbon-fibre composites from Tore Supra

Surface and bulk retention of deuterium in tiles of the pump limiter from Tore Supra was examined with nuclear reaction analysis using both standard and micro-beam techniques. The aim was to determine the variations in the content and distribution of fuel species in carbon-fibre composites. On plasma-facing surfaces from the deposition zone, the D content reaches 2.5 × 10 ¹⁹ cm ⁻² in about 8 μm thick top layer, but lateral differences reach even more than one order of magnitude. This is also measured in the erosion zone: 6.6 × 10 ¹⁷ cm ⁻² to 7.7 × 10 ¹⁸ cm ⁻² D atoms. Bulk content was examined on cross-sections opened by fracturing the tiles. Fuel is detected up to the depth of 1–1.5 mm beneath the plasma-facing surface in tiles from both the erosion and deposition zones. It occurs in bands, about 100 μm wide and several mm long, roughly parallel to the original plasma-facing surface.