Dynamics of the initial stage of discharge in air is studied at atmospheric pressure in a point–plane gap at different parameters of the tip electrode and lengths of the interelectrode gap. Spark or diffuse discharges are implemented in experiments depending on the length of the interelectrode gap. Shadow photography is used to show that, for all electrodes in the experiments, the discharge channels represent multiple microchannels that develop from the tip and close the discharge gap.

The authors created a device with a gliding unipolar arc of the Jacob’s ladder type. This paper presents investigation results of the arc ascent dynamics. It was found that the arc motion is uniform on the major part of its way. The arc ascent has the convection nature due to the air heating by the plasma. Dependence of the arc ascent velocity on the apex angle between the electrodes is obtained. The dependence is decreasing.