Photographs of a single shot discharge at the cylindrical and at the spherical composite anodes
are shown in Fig 8 a, and b, respectively. The pictures (U = 28 kV, C = 1 µF, solution conductivity
σ = 12 mS/cm) demonstrate the formation of a large number of channels with a high surface
density to form cylindrical and spherical pressure waves. The waveforms of the shock waves as
measured at the focus of the parabolic reflector for different applied voltages are shown in Fig.
9. A sensor with an active area of 4 mm2 was used