Electrical characteristics of the plasma filament generated by microsecond-pulsed underwater streamer discharges

Abstract

The underwater streamer discharges have a variety of potential applications in environmental science and technology. The electrical characteristics of the plasma filament generated by underwater streamer discharges play an important role in its propagation through water and influence the production of the chemical reactive species and the energy injected into the plasma filament. In this paper, we studied the electric field inside the plasma filament, the electric field at the head of the plasma filament, and the electrical conductivity of the plasma filament. By measuring the maximum length and the radius of the plasma filament, we found that the linear relation between the maximum length of the plasma filament and the applied voltage is not affected by the water conductivity within the range of 60–540 μS/cm. Based on such kind of linear relation, the electric field inside the plasma filament and the electric field at the head of the plasma filament were estimated as 26.0 ± 1.2 and 372 ± 52 kV/cm on average, respectively, being independent of the water conductivity within the range of 60–540 μS/cm. The electrical conductivity of the plasma filament was 0.4–3.7 S/cm within the range studied, being 3–4 orders of magnitude greater than that of the ambient water and depending significantly on the water conductivity. The experimental data obtained in the present work will be beneficial for the design of the reactor of pulsed underwater discharges.