Internal Microstructure of Current Channel of the Long Spark Discharge

Current channels formed in the long spark discharge in air at atmospheric pressure are studied using laser probing methods. The diagnostics includes laser interferometry, shadow and schlieren photographing. It was found that a thin (≈0.8–1 mm in diameter) current channel with internal microstructure is formed in the discharge under study. The microstructure appears in the inhomogeneous distribution of the refractive index in the current channel. The microstructure is formed in the leading channel region and is retained inside it for a long time (>400 ns).