Streamers in Water and Along the Insulator Surface in a Wire–Cylinder Gap

Two types of streamers in water, namely, volume streamers and surface streamers, have been observed in a coaxial discharge gap where the central anode wire was surrounded by a perforated dielectric cylinder inside the discharge gap. The speed of surface streamers (~ 100 km/s), which develops along the solid-liquid interface on the outer surface of the dielectric cylinder, exceeds that of the volume streamers (~ 42 km/s) by more than a factor of two. The axial surface streamers serve as sources for numerous thin secondary radial volume streamers.