Multi-factor Coupling Analysis of Short-Gap SF₆/N₂ Gas Discharge Process

In this paper, a two-dimensional axisymmetric model of an SF<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf>/N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> gas-mixed rod-plate structure with a 3.5mm gap is established based on hydrodynamic and gas discharge theory. By simplifying the Boltzmann equation into a set of fluid dynamics equations coupled with the Poisson equation, and combining the local field approximation with the Maxwellian electron energy distribution, the critical mechanisms and the dynamic distribution of the microscopic parameters of the electron avalanche transition under a non-uniform electric field are simulated and analyzed. The influence mechanisms of different voltages (10-20kV) and electrode curvature radius (0.5-1mm) on the streamer development are further explored.The results indicate that the electric field strength increases continuously during the electron avalanche stage and stabilizes during the streamer stage.Increasing the voltage accelerates the streamer development, increasing both the electron density and the field intensity, while increasing the curvature radius delays the streamer development and reduces the corresponding parameters. The study provides a theoretical basis for optimizing the SF6/N2 mixed gas insulation performance from the perspective of microscopic dynamics.