Underwater shock wave induced by pulsed discharge on water

Plasmas on liquids have provided significant applications in material, environmental, and biological sciences. The mechanisms of these chemical reactions in liquids have been primarily discussed by the plasma–liquid interactions and convection by an electrohydrodynamic flow. Although shock waves play a significant role in the radical formation, agitation, and cell destruction, not much information is available on underwater shock waves induced by the surface discharge on water. In this study, an underwater shock wave generated by the pulsed surface discharge on water using the laser shadowgraph method has been demonstrated. The results reveal that the shock wave generated by the discharge on water was transmitted into the water. The mean velocity of the shock wave reached 1.7 km/s. The results indicate that the surface discharge accelerates the reaction in the water by the combined action of the underwater shock wave and the plasma reaction at the air–water interface. The results are expected to aid in the understanding the mechanisms of existing applications, such as decomposition, synthesis, and sterilization.