300~4 000 K 下气体火花开关中 N₂ 及其与少量 O₂、H₂ 和 Xe 混合气体的击穿性能

N₂ is the most commonly used insulating gas in gas spark switches, and sometimes, a small amount of additive gas is added to improve the insulating and switching performance. In this paper, the dielectric properties of N₂ and its mixtures with O₂, H₂, or Xe at 0.1 MPa and a gas temperature range of 300~4 000 K were evaluated. Firstly, the equilibrium composition of hot N₂ and its mixtures was calculated using the Gibbs free energy minimization method. The electron energy distribution function was derived by solving the Boltzmann equation, and the reduced ionization coefficients, attachment coefficients and effective ionization coefficient were acquired accordingly. The calculated effective ionization coefficients at room temperature were also compared with those obtained by the pulsed Townsend experiments. The theoretical and experimental data of N₂-H₂ and N₂-Xe were reported for the first time. Finally, the critical reduced electric field and reduced breakdown electric field were calculated to evaluate the dielectric strength and dielectric recovery capability of the gas after breakdown. The breakdown voltage was calculated by the effective ionization coefficient and combined with the gas spark switch for the first time. The results demonstrate that the reduced critical electric-field-strength of the N₂-O₂ mixture decreases with increasing temperature up to 2 500 K, before which the reduced critical electric-field-strength remains unchanged. The results show that N₂-H₂ and N₂-Xe have a strong ability to restore the dielectric properties and are suitable for repetitive pulsed switches. The results are intended to help the design and engineering application of gas spark switches.