Depth Profile Measurements of Hydrogen Isotopes near the Surface of the TFTR Plasma Facing Component using Nuclear Reaction Analysis

Abstract

Tritium and deuterium depth profiles of the TFTR tile exposed to deuterium-tritium plasmas have been measured to reveal the hydrogen isotope behavior at the surface region by means of deuteron induced nuclear reaction analysis. The analyzed sample was a part of a tile made of a four-dimensional carbon fiber composite, which was placed at K bay, column C, row 16 of the TFTR vacuum vessel. Four kinds of elements, deuterium, tritium, lithium -6 and lithium -7, were identified. The tritium concentration had a peak at 0.5 μm with an atomic density of 7.4×10²⁵ T/m³ in depth profile, whereas the deuterium showed a broad distribution up to the depth of 1.5 μm with atomic densities of 3.4×10²⁷ D/m³. It is found that a fraction of the retained tritium from the surface to 1.5 μm, 8.1×10¹⁹ T/m², corresponded to 2% of that from the surface to 1 mm, 1.0×10²¹ T/m², which was measured for the KC-18 tile using the combustion method.