Transient Processes During Formation of a Steady-State Glow Discharge in Air

This paper describes the investigation of an atmospheric-pressure glow discharge in air at a current of 0.05-0.3 A. Before the glow discharge is established, a preliminary nonsteady temporal stage is available in the gap. The principal process, which governs with the nonsteady-state discharge behavior, is the glow-to-spark transition phenomenon. The transition is initiated due to the explosive emission instability in the near-cathode layer of glow-type discharge that results in a microexplosion of the cathode surface and appearing of a spark cathode spot. At a low current, the spot is extinguished, so that the discharge starts burning again in one of the glow modes. After that, a new act of transition occurs and so on. The preliminary nonsteady-state stage ensures two prerequisites. First, an effective gas pressure decreases to a low value. Second, due to microexplosions, conditioning of the cathode surface is provided. Both factors facilitate establishing the normal glow discharge.