Shock Waves Generated by an Electrical Discharge on Composite Electrode Immersed in Water With Different Conductivities

A generation of focused shock waves by underwater multichannel pulsed electrical discharge on a porous-ceramic-coated electrode in saline water is studied. This work describes the effect of solution conductivity of saline water on the pressure of shock waves. It was found that the amplitude of shock waves has a nonlinear dependence on water conductivity: The amplitude increases with the increase of water conductivity up to 18-20 mS/cm and then decreases again. In this paper, we show that two effects take place. First, the electrical energy dissipated in the discharge depends on the impedance of the electrode system being affected by water conductivity. Second, the velocity of streamer growth strongly depends on energy deposition time into the discharge. The two mentioned effects result in "hill-like" shape of the curve presenting the dependence of the maximum amplitude of the shock wave on water conductivity.