High field light emission in LDPE/MgO nanocomposite

This paper deals with initiation of light emission and electrical trees in LDPE/MgO nanocomposite. Specimens were prepared in such a way that a tungsten needle of 50 mum phi and 1mumR was inserted into dielectrics with a spacing of 0.4 mm between high voltage and ground. Light emission was observed by an ICCD camera, and tree shapes were examined by an optical microscope. As a result, it was found that light emission originates from electrical trees rather than electroluminescence in our experiments and that initiation of electrical trees and light emission are affected by the addition of nano MgO fillers. That is, it was clarified that applied voltage or electric stress for tree initiation tends to increase, as filler content increases in the range of 0 to 1 phr. In addition, tree length is shortened due to inclusion of nano-fillers.