High voltage pulse electrical discharges in water solutions have been studied using different geometries of electrodes. It was demonstrated that discharges in all electrode configurations used (needle - plate, coaxial composite anode - tubular cathode and coaxial pinhole anode tubular cathode) produce plasmas with very similar parameters.
Plasma electron density depends strongly on the solution conductivity. Discharges in water have no counterpart in gas phase ones.
The main chemically active specie produced by corona-like discharges is hydrogen peroxide, other species as H, O and OH radicals play a minor role. Degradation of phenol and decolorizing of organic dye "reactive blue 137" by OH radicals have been demonstrated.
Corona-like discharges may find some applications in solution of environmental problems. At very high solution conductivity (5 - 20 mS/cm) multi-channel discharge with the composite anode generates strong acoustic waves.
Focusing of the cylindrical pressure wave by parabolic metallic reflector and generation of spherically convergent wave has been demonstrated. Strong shock waves that lead to cavitation are formed at the focus region.
Interaction of focused shock waves with cellular scale structures have been demonstrated. We believe that the focused shock waves will find some applications in medicine.