Thin Luminous Tracks during a Nanosecond Discharge in a Nonuniform Electric Field

The glow of a nanosecond diffuse discharge between two tips with high spatial resolution has been studied. At atmospheric air pressure, as well as at pressures of 300, 100, and 30 Torr, a large number of thin luminous tracks, starting from the region of bright spots on the electrodes, have been discovered. It is shown that the shape of the tracks changes from straight lines to winding ones, and the direction of their movement in some cases changes to the opposite. It is shown that, under conditions of the formation of thin luminous tracks, the bands of the second positive nitrogen system dominate in the emission spectrum of diffuse plasma with a sharply inhomogeneous electric field and nanosecond duration of the voltage pulse. Using an ICCD camera, it has been shown that no emission of the tracks is detected during the first tens of nanoseconds against the background of wide streamers and a diffuse discharge. A hypothesis has been put forward to explain the appearance of numerous tracks during air breakdown in a nonuniform electric field.