shows a scheme of the experimental setup. The shock wave
generator consisted of a cylindrical high-voltage composite electrode
(anode) placed along the axis of the outer metallic parabolic reflector
(cathode) [57]. The dimension of the cylindrical composite electrode
was 60 mm diameter × 100 mm long. The generator was divided into
two sections by an acoustically transparent membrane (Mylar foil).
The inner part was filled with a highly conductive saline solution
(18 mS/cm) and a contained electrode system. The focal point of the
Fig. 1. Scheme of shock wave generator.
104 P. Lukes et al. / Bioelectrochemistry 103 (2015) 103–110
reflectorwas situated in the outer part of the generator,whichwas filled
with tap water and was located 70 mm above the reflector aperture. A
high voltage pulse of positive polarity with an amplitude of 21 kV was
applied to the composite electrode charged from the pulse power supply,
which consisted of a high voltage direct current (DC) source
(model EW30P20, Glassman High Voltage, Inc.), a charging capacitor
of 0.8 μF, and a spark gap switch. An underwater electrical discharge
plasma at the surface of the high-voltage cylindrical electrode produced
a primary cylindrical pressure wave which propagated into the liquid
perpendicular to the cylinder axis. This cylindrical pressure wave was
focused by the parabolic reflector to a common focal point and transformed
into a shock wave at the focus.