Performance of functional materials and components in a fusion reactor: The issue of radiation effects in ceramics and glass materials for diagnostics

Reliable plasma diagnostics systems are key elements for an efficient operation of future fusion reactors. They represent a major challenge, as existing systems must be upgraded to the harsh environment of a burning plasma and to the stringent requirements of real-time control actions. Radiation effects bring in this respect specific constraints. The front ends of most of the diagnostics systems are inside the vacuum vessel, and therefore subject to intense neutron and γ radiations. These systems use particular components, such as ceramic insulators, dielectric and optical windows, optical fibres and complete sensor assemblies. Studying radiation effects for these components requires particular attention to the material choice and a specific methodology. The paper makes a review of the research performed worldwide on this subject and discusses the state of the art and the future priorities to be set.