Quantitative thermal imperfection definition using non-destructive infrared thermography on an advanced DEMO divertor concept

The future DEMO divertor is currently under conceptual design within the European Consortium. In this regard, several concepts have been proposed and mock-ups have been fabricated to investigate their thermo-mechanical behaviour. Indeed, as a key plasma facing component, the divertor will have to withstand extreme thermal loads (up to 20 MW m⁻² during slow transient events) and will have to be able to exhaust a large amount of heat. The presence of structural defects in the component may significantly affect the thermal response and must therefore be considered. A non-destructive technique based on infrared thermography is proposed here to detect defects in mock-ups where graded material was used as an interlayer between the heatsink material and the armor material. Two methods to characterize the size and location of such defects are presented. It was shown that finite element analysis combined with experimental data from infrared thermography, provides accurate means to assess quantitatively the size and position of thermal imperfections. (paper)