Simulation Study on the Pre-Breakdown Process of Underwater High-Voltage Pulsed Discharge Based on Field-Induced Ionization Theory

Pulse discharge in water has been widely applied in various fields due to its physical and chemical properties. However, the morphology of the discharge pre-breakdown process is influenced by multiple parameters, which in turn affect the form of discharge in water and energy conversion. Based on the theory of field ionization, we established a simulation model for the pre-breakdown process of discharge in water under nanosecond pulse voltage. The development of the streamer during pre-breakdown process were studied, which can be divided in to four stages: initiation, distortion, transition, and breakdown. Results demonstrate that elevated voltage amplitudes or reduced electrode gaps intensify needle-tip electric fields, accelerating water ionization and expediting streamer formation, while stronger tip fields concurrently promote branching phenomena at the primary streamer. Furthermore, a smaller curvature radius of the needle tip will also increase the field strength of the needle electrode and change the trajectories of branch streamer. This study elucidates the effects of discharge parameters on pre-breakdown processes in underwater high-voltage pulsed discharges, thereby offering theoretical guidance for the application and parameter optimization.