Observation of Underwater Streamer Discharges Produced by Pulsed Power Using High-Speed Camera

Abstract

Pulsed power, used to produce underwater discharges, has been the subject of numerous studies to elucidate its mechanisms and applications. This paper reports on observation by a high-speed camera of the production and progress of streamer discharges created using a magnetic pulse compression pulsed power generator with maximum output energy of 40 Joules per shot in the medium of both tap and distilled water. Bubble production along streamers, bubble collapse, generation of shock waves, and extinction of bubbles was also observed by a high-speed camera.

Numerical Study on Bubble Dynamic by Pulsed Electric Discharge in Water

“…10 (d)-(f) of Ref. [5], the main bubble remains generally with expansion in almost spherical shape. It could be believed that the gaseous filaments insulate from the main bubble, and shrink starting from 182.2 μs.…”

“…10 (a)-(d) of Ref. [5], the gaseous filaments become shorter and thicker, and merge into the main bubble till 182.2 μs. Therefore, till 182.2 μs, the main bubble is in the unstable growth phase, and it is difficult to consider the surface tension act to the main bubble due to high pressure inside the gaseous filaments.…”

“…10 of Ref. [5], where (a)-(f) are taken at 2.2 μs, 22.2 μs, 82.2 μs, 182.2 μs, 320.2 μs, and 442.2 μs, respectively. It indicates two aspects: one is the coalescence of gaseous filaments to a main bubble in the growth phase.…”

“…However, the streamer-induced bubble attaches to the electrode tip, and expands by gaseous filaments collection. Akiyama et al [5] have presented experimental studies on streamer-induced bubble.…”

“…The stand-off parameter γ was a choice based on the experimental data of Ref. [5]. The jet velocity impact on the solid surface has been calculated, which can generate a high localized pressure with short duration.…”