Abstract: The ignition of spark gaps for the production of shockwaves in the contactless comminution of concrements, using a capacitor discharge is improved by providing at least for some time prior to the ignition proper a voltage much smaller than the breakthrough voltage for producing a small current between the electrodes that prepares a channel in the discharge gap.

Abstract: A shockwave source and generating device includes a ring shaped or cylindrical wave generator having a central axis for radiating shockwaves in an axial direction or radially towards a parabolic reflector so that any yet unreflected radiation from the generator is intercepted by the reflector and reflected towards a focal point on that axis.

Abstract: An arrangement for the comminution of concrements of various kinds in the body of living being, uses an underwater or submerged arc gap with spark discharge, and an electrical energizing circuitry for that arc gap, a plurality of electrode assemblies from which one is selected to be used in the equipment is connected to the energizing circuit; the electrode assemblies are basically similarly configured and each has an ohmic resistor which is connected directly in series with one of the electrodes, the resistance value for the resistors in the electrode assemblies of the plurality are different, and in each instance much lower than the resistance of the unignited gap, but of comparable magnitude with the resistance of a fully developed plasma channel in the gap following ignition by the energizing circuit.

Abstract: A piezoelectric shock wave generator for use in medical equipment includes a plurality of piezoelectric elements being electrically interconnected to operate in parallel and mounted on a common carrier of curved configuration; a coupler medium couples shock waves as generated by these piezoelectric generators into the body of a living being, the improvement includes electrical insulation between the piezoelements being in fluid, i.e. liquid or gaseous state, in that each piezoelectric element is surrounded by the fluid in any direction towards any other piezoelectric element; the front ends of the piezoelectric elements may be physically separated, so that the coupler fluid and the isolating fluid are the same, and having a common flow space; alternatively, a membrane in front of all said piezoelectric elements provides electrical interconnection between them and physically separates the isolating fluid from the coupler liquid.

Abstract: An underwater electrodes assembly for contactless lithotripsy is suggested wherein two electrodes have tips facing each other across a narrow gap and at least one, preferably both, electrodes are surrounded by sleeves or rings made of a dielectric material, such as a thermoplastic.