Influence of hydrostatic pressure on the characteristics of single-pulse discharge plasma in water

Liquid-phase plasma is widely used in industry, so it is important to study its characteristics. In this paper, an experimental system utilizing a cylindrical pressure tank with adjustable hydrostatic pressure for studying liquid-phase pulsed discharge plasma is designed, and the components and experimental principles of the system are introduced in detail. Based on this experimental system, the influence of hydrostatic pressure on the characteristics of liquid-phase plasma was investigated under varying voltage levels and electrode spacings. The results demonstrate that the experimental system can effectively generate and observe liquid-phase plasma. As hydrostatic pressure increases, the pre-breakdown delay at 15 kV and a 2 mm electrode gap increases from 25.6 μs at 0.1 MPa to 447.2μs at 0.5 MPa, while the duration of the main discharge stage decreases from 224.4 to 210.4μs. At 13 kV with a 2 mm electrode gap, the emission spectrum intensity and the electron density of the discharge plasma decrease with increasing hydrostatic pressure. The electron temperature in the plasma channel ranges from 11,000 K to 16,500 K. In addition, the discharge process phenomena were analyzed using typical high-speed camera images, highlighting the characteristics of the discharge plasma at each stage. Finally, the shortcomings and improvement of the experimental system are analyzed.