The Influence of Gamma Irradiation on Space Charge in LDPE

In the present paper, we report an investigation on the effect of radiation environment on space charge in low density polyethylene (LDPE). LDPE thin films of ~100 mum were irradiated at a dose rate of approximately 1 kGy/h using a
⁶⁰
Co gamma source. The samples were irradiated in air, vacuum and nitrogen gas at room temperature to various doses from 5 to 100 kGy. Space charge measurements were carried out using the pulsed electroacoustic (PEA) technique. The applied electric field in all cases is 50 kV/mm. It has been found that the space charge dynamics in the irradiated samples are different from the fresh (un-irradiated) sample and affected by irradiation environment. Although the oxidation of the samples in air may play an important role in the observed differences, charge dynamics in the samples irradiated in vacuum and pure nitrogen gas are also different