The glow-to-arc transition of a convection-stabilized atmospheric pressure air discharge is numerically investigated. Two separate models are considered: a one-dimensional axisymmetric time-dependent fluid model of the positive column, describing the thermal-instability, and a sheath model of a cold cathode describing the field-emission instability, which must then be properly matched together. The fluid model considers the most important chemical reactions in air plasma, including thermal ionization in atomic collisions. The radial electric field in the plasma is obtained from the Poisson equation. The voltage–current characteristic of the discharge is simulated for a time-varying current up to 300 mA. It is found that at some critical value slightly above 200 mA, the contraction of the positive column arises from a vibrational–translational energy relaxation. The subsequent increases in the discharge current density in the positive column drive in turn a field-emission instability in the cathode, which is accompanied by a large voltage drop. Simulation results are validated against available experimental data.

对对流稳定大气压空气放电的辉光到电弧的转变进行了数值研究。考虑两个单独的模型：描述热不稳定性的正柱的一维轴对称时间相关流体模型和描述场发射不稳定性的冷阴极的鞘模型，然后必须将它们正确地匹配在一起。流体模型考虑了空气等离子体中最重要的化学反应，包括原子碰撞中的热电离。等离子体中的径向电场由泊松方程获得。针对高达 300 mA 的时变电流来模拟放电的电压-电流特性。研究发现，在略高于 200 mA 的某个临界值处，正柱的收缩是由振动平移能量弛豫引起的。随后正极柱驱动中放电电流密度的增加又导致阴极中的场发射不稳定，并伴随着大的电压降。模拟结果根据可用的实验数据进行验证。