ELECTRICAL-PROPERTIES OF AL2O3 DURING IRRADIATION WITH SPALLATION NEUTRONS

DC and AC conductivity of Al2O3 ceramics were measured at elevated temperatures during irradiation with neutrons and gamma rays at the Los Alamos Spallation Radiation Effects Facility. DC conductivity increased at start of irradiation, but subsequently reduced as displacement damage was accumulated. AC conductivity appeared to increase at high levels of damage. The observed DC behavior is attributed to excitation of electrons into the conduction band by ionizing radiation, followed by charge trapping and recombination at damage sites. The AC behavior, which resembles RIED, is attributed to a combination of surface conductivity and conductivity in the residual gas surrounding the samples. These results have design implications for fusion-reactor systems.