Influence of Solid Dielectric Permittivity on Positive Streamer Characteristics in a Liquid-Solid Composite Dielectric

This paper presents a numerical investigation of positive streamers in a liquid-solid composite dielectric system, specifically in the context of wet-mate DC connectors. The study focuses on the influence of different materials and relative permittivity values of the solid dielectric on streamer behavior. The study employs a non-dimensionalized electric field-dependent molecular ionization streamer model to describe the initiation and propagation of streamers within a needle-sphere electrode system. A 2D-axisymmetric COMSOL model is utilized, where a solid tube-like dielectric is placed near the needle tip in an electrode system filled with transformer oil. The effects of varying relative permittivity values on the electric field distribution, streamer propagation velocity, ionization and attachment rates, and spatiotemporal evolution of charged species (electrons, positive ions, and negative ions) are studied. By analyzing these aspects, the paper aims to enhance the understanding of streamer dynamics and provide valuable information for optimizing the design and performance of equipment utilizing liquid-solid composite dielectric systems.