Formation of electrical treeing in polyethylene

In our earlier paper [1] we have presented a new model for electrical treeing in polymers. This model states that electrons and holes can be injected into the polymer from a metallic needle electrode either by tunneling via localized states or by thermionic emission, and that these injected charge carriers will form space charges which will then modify the electric field distribution and produce channels of lower density by mutual repulsion and dissociative recombination to create a favorable condition for impact ionization. These processes will lead to the formation of electrical trees. The present paper will present some new experimental results in support of this model.