The mechanism of gas pressure and temperature dependent surface flashover in compressed gas involving gas adsorption

Abstract

In surface science, when a high voltage is applied, a penetrating discharge occurs along the gas-solid interface, which is called surface flashover. Although the electron stimulated gas desorption is a crucial process for surface flashover in vacuum, the underlying gas-solid interaction physics process for surface flashover is still ambiguous in compressed gas. In this study, the effect of gas adsorption on surface flashover is taken into consideration, surface flashover voltage, gas breakdown voltage, gas adsorption quantity are tested at various gas pressures and temperatures in N2, and the surface gas density is calculated. It is found that the difference between surface flashover voltage and gas breakdown voltage (Vf/Vb) has a positive correlation with the relative gas adsorption ability (Va×T/p or Nsur/Nav) in a wide gas pressure, temperature and density ranges. The results indicate surface flashover occurs in the gas adsorption layer, which density is higher than the average gas density in the gas phase. The gas adsorption improves the surface flashover voltage by impeding electrons collision ionization process in compressed gas. The findings in this research provide a new perspective for studying surface flashover, and offer a route to improve surface flashover performances by tailoring surface adsorption characteristics.