Dynamic of a Space Charge in Gamma-Irradiated Cross-Linked Polyethylene (XLPE)

The aim of the present work is to study the dynamics of the space charge in cross-linked polyethylene (XLPE) irradiated by gamma rays. For this purpose, film samples peeled from cables have been irradiated with gamma rays at total dose up to 100 kGy, in air at room temperature. To investigate the impact of the irradiation on the electrical behavior, space charge measurements were achieved in ambient conditions after the irradiation using Pulsed Electro Acoustic (PEA) method. The space charge measurements on the irradiated XLPE under an electric field of 40 kV/mm show the development of two-heterocharge regions adjacent to the electrodes. This is in mark contrast with the behavior of un-irradiated XLPE with space charge pattern dominated by charge injection. The charge accumulated during the polarization step persists during the relaxation and is stable after 1 hour.