Radiation effects and damage mechanisms in ceramic insulators and window materials

The effect of radiation on the properties of ceramic insulators for fusion reactor applications is considered. The various displacement damage mechanisms are described and particular attention paid to the concept of a displacement damage efficiency, k, and the displacement threshold energy Ed. It is found that in the refractory oxides k is temperature dependent with values of 0.4 for T < 80 K, 0.1 for T ≅ 300 k and 0.05 for T > 450 K. The effects of transmutation products on defect aggregation and material properties are discussed. Then the electrical behaviour of ceramic insulators is considered with particular attention being paid to radiation-induced dc conductivity and dielectric loss at high frequencies. (orig.)