Thermal and neutron tests of multilayered dielectric mirrors

ITER optical diagnostics require mirrors for light transmission from plasma to detectors. These components will be exposed to significant fluences of fast neutrons during D–T operation. Two types of dielectric mirrors made of alternating layers of TiO2/SiO2 and ZrO2/SiO2 on silica glass substrate were irradiated to a fluence of 1019 n/cm2 in water-moderated nuclear reactor at ambient water temperature 50 °C. Irradiation test was preceded by heating the samples up to 280 °C. In result, all the samples retained their optical properties and structural integrity under irradiation, some of them showed structural degradation during heating.