Electrical conductivity of Wesgo AL995 alumina under fast electron irradiation in a high voltage electron microscope

Electrical conductivity of a 295-μm-thick Wesgo AL995 alumina has been measured before and during 1 MeV electron irradiation in a dc electric field of 300 kV/m at temperatures up to 723 K. The difference between the activation energies before (0.49±0.02 eV) and during (0.19±0.06 eV) irradiation indicates a substantial impact of irradiation on the conductivity of Wesgo AL995 alumina. The electrical conductivity of Wesgo AL995 alumina is lower by approximately 2 orders of magnitude than its requirement for the magnetic coils in the international thermonuclear experimental reactor (ITER). Thermal disruption may not impact on Wesgo AL995 alumina insulating material in ITER because of the absence of thermally stimulated conductivity peaks in it. Although no substantial bulk degradation is observed under irradiation up to a fluence of 7.0×1022 e/m2 (7.97×10−5 dpa) at 723 K, surface degradation is detected that could limit the application of Wesgo AL995 in ITER as a potential insulator.