Space charge and dielectric breakdown in polypropylene

Quantitative probing of space charge and breakdown strength measurements were carried out on polypropylene (PP) at room temperature. A positive space charge due to injection was formed at low fields. Electrons are injected and form a homo space charge either in the high field region or when the cathode field is enhanced by the positive space charge extended from the anode. It was concluded that at room temperature the breakdown is initiated by the injected electrons and it mainly takes place in the region near the cathode. Effects of physical structure on the space charge behaviour is also under investigation.