On the formation of a bead structure of spark channels during a discharge in air at atmospheric pressure

Abstract

The conditions for the formation of spark channels with a bead structure in an inhomogeneous electric field at different polarities of voltage pulses are studied. Voltage pulses with an amplitude of up to 150 kV and a rise time of ≈1.5 µs were applied across a 45-mm point-to-plane gap. Under these conditions, spark channels consisting of bright and dim regions (bead structure) were observed. It is shown that when current is limited, an increase in the rise time and the gap length does not affect the formation of the bead structure. It was found that an increase in the amplitude of voltage pulses leads to an increase in the length of beads. The appearance of the bead structure is more likely at negative polarity of the pointed electrode. The formation of spark channels was studied with a four-channel ICCD camera.