SURFACE AND VOLUME ELECTRICAL DEGRADATION IN WESGO AL995

Radiation-enhanced electrical surface degradation has been observed in Wesgo AL995 alumina when irradiated with 1.8 MeV electrons in high va cuum with an applied electric field. Ionizing radiation and the vacuum environment play key roles in the degradation. The difference between this alumina and Vitox 999, which shows no surface degradation, may b e related to the Wesgo lower purity, larger grain size, and lower dens ity. The observations help to explain some of the conflicting results for radiation-induced electrical degradation (RIED), and draw attentio n to the need to consider this environmental effect when performing RI ED experiments on insulators for fusion applications.