Discharge Inception in Hydrocarbon Liquids: Effect of Electrode Surface Roughness

The effect of microprotrusions at electrode surfaces on the discharge inception in hydrocarbon liquids in corona-like gap configurations is considered. The inception field is estimated for cylindrical protrusions of various lengths and radii. Agreement of evaluated inception fields with experimental data for rods with radii of about a centimeter is achieved for protrusions with lengths and radii of 20– $50~\mu \text{m}$ and 1– $2~\mu \text{m}$ , respectively. These protrusion parameters are close to those obtained previously by analysis of discharge inception in compressed gases.

I. Introduction

Discharge development in dielectric liquids is a complex phenomenon, its character depending on liquid nature, discharge gap configuration and dimensions, polarity, duration and amplitude of applied voltage pulse, and so on [1]–[4]. Breakdown of liquids is often accompanied with phase transition, including the stages of formation of bubbles and propagation of filamentary gaseous channels. In most of cases, the mechanism governing the initial stage of discharge inception is ionization of molecules by electron impact in liquid phase [3].