Formation and annihilation characteristics of space charge in PE/EVA interfaces

Interfacial space charge was measured for laminated dielectrics by the laser-induced pressure pulse (LIPP) method. Specimens used for experiments consisted of low-density polyethylene (LDPE) and ethylene vinyl acetate (EVA) of thickness 0.25 mm each and were subjected to d.c. voltages up to 10 kV. The voltage was continuously applied until the space charge in the interface increased nearly to the saturation of the charge accumulation. It was clarified that the space charge formed at the interface between the two dielectrics was around 10 to 100 μC/m ², which was smaller than the induced electrode charge, and was long-lived after the cessation of voltage with more than two kinds of decay times. The process for formation and annihilation of interfacial space charge is presented