The mechanism of air ionization by a single nanosecond discharge under atmospheric conditions is studied using numerical simulations. The plasma kinetics are solved with ZDPlasKin and the electron energy distribution function is calculated with BOLSIG+. The model includes the excited electronic states of O and N atoms, which are shown to play the main role in plasma ionization for n _e > 10¹⁶cm⁻³. For electric fields typical in nanosecond discharges, a non-equilibrium plasma (T _e > T _gas) is formed at ambient conditions and remains partially ionized for about 12 nanoseconds (n _e < 10¹⁶cm⁻³). Then, the discharge abruptly reaches full ionization (n _e ≈ 10¹⁹cm⁻³) and thermalization (T _e = T _gas ≈ 3eV) in less than half a nanosecond, as also encountered in experimental studies. This fast ionization process is explained by the electron impact ionization of atomic excited states whereas the fast thermalization is induced by the elastic electron–ion collisions.

使用数值模拟研究了大气条件下单纳秒放电的空气电离机制。等离子体动力学使用 ZDPlasKin 求解，电子能量分布函数使用 BOLSIG+ 计算。该模型包括 O 和 N 原子的激发电子态，显示在n _e > 10 ¹⁶ cm ^{-3 的}等离子体电离中起主要作用。对于纳秒放电中典型的电场，在环境条件下形成非平衡等离子体（T _e > T _气体）并保持部分电离约 12 纳秒（n _e < 10 ¹⁶ cm ^-3）。然后，放电在不到半纳秒内突然达到完全电离（n _e ≈ 10 ¹⁹ cm ^-3）和热化（T _e = T _gas ≈ 3eV），这在实验研究中也遇到过。这种快速电离过程可以通过原子激发态的电子碰撞电离来解释，而快速热化是由弹性电子 - 离子碰撞引起的。