Hydrogen isotope inventories in the ASDEX Upgrade tungsten coated divertor tiles

Abstract

The total hydrogen isotope inventories in the tungsten coated divertor tiles of ASDEX-Upgrade were measured by thermal desorption spectroscopy (TDS) and – in the near surface region – by nuclear reaction analysis (NRA). The highest amounts of deuterium (⩽5 × 10 22 D/m 2) are measured in the inner divertor region outside the separatrix due to the formation of a C:H layer on the tungsten by codeposition of deuterium with carbon. The inventories in the outer divertor – where erosion dominates – are generally smaller by an order of magnitude.