Laser-induced pressure pulse measurements of space charge in PE/EVA laminates

The LIPP method was used for measuring the charge distribution at the interface between PE/EVA laminate dielectrics under dc stress. High power laser light of 300 mJ/pulse was applied to a specially coated surface of the specimen. A short (300 ps) and a long (5 ns) laser pulse were used for thin and thick specimens, respectively. The result of the measurement shows that space charge was accumulated at the interface, When it was positive, the space charge stayed at the interface on the EVA side and was not transferred to the interface on the LDPE side. On the contrary, when it was negative, the space charge was transferred to the interface on the LDPE side.