Formation of a small ‘bead lightning’ in a half-microsecond discharge in air

• Published in: Physics letters. A 2019-01, Vol.383 (4), p.351-357
• Main Authors: Beloplotov, D.V., Tarasenko, V.F.
• Format: Article
• Language: English
• Subjects: Bead lightning; Nanosecond discharge; Runaway electrons; Spark discharge; Streamer
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/j.physleta.2018.11.004

The formation of periodic plasma clots which form a discharge channel similar to bead lightning has been studied with a four-channel intensified charge-coupled device (ICCD) camera simultaneously with the recording of voltage and current waveforms. It was found that a diffuse discharge was formed at the initial stage due to the development of a wide streamer. Runaway electrons were registered. Beads were formed as a result of the development of the spark leader after the diffuse stage. It was assumed that the diameter of the spark leader periodically changes in accordance with the change in the electric field strength in the spark leader head. As a result, narrow sections of the channel heat up more and glow brighter. •A discharge similar to bead lightning was realized in a point-to-plane gap filled with air at applying half-microsecond voltage pulses.•A streamer with large transverse dimensions developed at the initial stage and a diffuse discharge was formed.•Bead structure was formed at the initial stage of the spark formation due to the development of a spark leader during the fading of the diffuse discharge.•The formation of beads occurs, perhaps, due to the periodic change in the diameter of the spark leader during its propagation.