INVESTIGATIONS ON CERAMIC MATERIALS FOR FUSION TECHNOLOGY

Thermophysical and mechanical properties were measured on SiC as an irradiation-resistant First Wall (FW) protection material and on various low loss microwave window materials. An evaluation shows that SiC may not to be excluded from use for FW protection, but only moderate plasma disruption impacts could be tolerated. For the HF window development several grades of alumina, A1N, and spinel were extensively tested for their thermal and mechanical properties and with respect to HF absorption at ≈ 145 GHz. Alumina and particularly sapphire are superior in dielectric properties, but if thermal stresses are taken into account, the best grades of A1N are preferable. This could be demonstrated by parametric lifetime calculations for windows of a given design. The tolerable HF power densities are, however, still unsatisfactory. Irradiations deteriorate both thermal conductivity and dielectric loss. © 1990.