Electrical Conduction and Space Charge in Gamma-Irradiated XLPE

It is well known that ionizing radiation impact dielectric and mechanical properties of polymers, as a result of chain scission, crosslinking, and oxidation steps. The electrical conductivity is generally substantially increased after irradiation. We analyze such effects in cross-linked polyethylene (XLPE) after gamma-irradiation. Current measurements reveal a substantial increase in conductivity after irradiation at doses up to 200 kGy. Current-field characteristics change after irradiation and appear indicative of an ionic-type conduction. Space charge measurements confirm the mechanism with obvious heterocharge build-up after irradiation.