Charge transfer evaluation in solid insulating materials encapsulating the gaseous voids of submillimeter dimensions using transmission line method

Abstract

: In this work, using a lumped RC circuit model which is based on transmission line modeling (TLM) method, the charge transfer in a solid insulating system encapsulating a gaseous void of submillimeter dimensions is evaluated. Here, both the dielectric material and gaseous void are considered simultaneously as a transmission line. The transmission line includes the capacitive and resistance elements and, the obtained circuit equations were coupled with the continuity and kinetic energy equations for charged species along with Poisson’s equation. These equations are solved via 4th order Runge-Kutta method and, the electric field and potential, density of all the charged species, discharge current and electron temperature are calculated in the gaseous media. Hence, the discharge propagation in the gaseous void and its mutual influences on dielectric medium are described. The partially penetration of electrons in the avalanche head into the anode dielectric bulk is shown, and it is observed that their movements towards the electrodes are much faster than ions. Besides, the total transferred charge particles at both the avalanche and streamer phases in the void is calculated. Besides, it was found that, the electrons temperature distribution completely influenced by electric field in the gaseous void. In addition, the effects of voids thickness and their location on the discharge current are examined. It is shown that, at the higher void thicknesses and for the cavities locating in the electrodes adjacent, the magnitude of discharge current increases