Experimental developments towards an ITER thermography diagnostic

Abstract In the course of the development of a concept for a spectrally resolving thermography diagnostic for the ITER divertor using optical fibres experimental development work has been carried out in three different areas. Firstly ZrF 4 fibres and hollow fibres (silica capillaries with internal AG/AgJ coating) were tested in a Co 60 irradiation facility under γ irradiation up to doses of 5 kGy and 27 kGy, respectively. The ZrF 4 fibres suffered more radiation induced degradation (>1 db/m) then the hollow fibres (0–0.4 db/m). Secondly multi-colour pyroreflectometry is being developed towards tokamak applicability. The emissivity and temperature of tungsten samples were measured in the range of 700–1500 °C. The angular working range for off normal observation of the method was 20–30°. The working distance of the method has been be increased from cm to the m range. Finally, encouraging preliminary results have been obtained concerning the application of pulsed and modulated active thermography.