Broadband dielectric mirrors for optical diagnostics in ITER

摘要

Specially designed multilayered dielectric mirrors are able to provide reflectivity over 95% in visible range and hence can help to improve the performance of optical diagnostics for use in ITER. Samples with TiO_2/SiO_2 and Nb_2O_5/SiO_2 coatings were tested under heat loads following neutron irradiation to verify their resistance to ITER-relevant conditions. All samples survived the neutron irradiation. Reflectivity of TiO_2/SiO_2 samples degraded after heating, whereas Nb_2O_5/SiO_2 samples showed no significant changes in all the tests. Additionally, influence of hydrocarbon contamination on samples reflectivity was experimentally examined. As a result, such an effect was found not to be significant, and Nb_2O_5/SiO_2 coating is regarded to be acceptable for ITER applications.