Pulsed electro-acoustic measurement of volume charge accumulation and decay in polyethylene

The measurement of volume charges within solid insulators provides needed information important to the evaluation of dielectric performance and the modelling of breakdown processes. Furthemore, electrical insulation such as polyethylene can be crosslinked with penetrating electron irradiation and thus be exposed to charge injection. While polyethylene is a widely used dielectric material, especially in cables, there is little direct information about its charge retention capabilities or the magnitude and distribution of residual charges which accumulate during the radiation process. Some studies of space charges in PE have employed electro-optic methods,[1] but they required the PE to be heated to softening temperatures so as to make it sufficiently transparent for the optical measurement. In this study, the pulsed electro-acoustic method [2,3] was used on samples at room temperature and below to non-destructively determine and monitor the volume charges in PE.