Laser desorption of deuterium retained in re-deposited carbon layers at TEXTOR and JET

ITER operation might be limited by the tritium inventory that will be retained in carbon tiles and re-deposited carbon layers. Means to determine in situ the tritium content of these layers and also the deuterium content in the nonactivated phase of ITER and tritium recovering techniques have to be developed. This paper describes an approach in which the thickness and deuterium (tritium) content of re-deposited carbon layers is determined by local laser heating. This leads to the release of the retained fuel by evaporation and, depending on the laser power density even to the removal of the layer itself. An essential element of this method is the quantitative determination of the released particles by local spectroscopy in the edge plasma. Results from this method from experiments in the laboratory, and on TEXTOR and JET are described in this paper. (c) 2004 Elsevier B.V. All rights reserved