The thermohydraulic generator: a pulse power source of intense pressure pulses

Intense pressure pulses, often focussed to form strong shockwaves, are used for a variety of medical and industrial applications. In this contribution, a new principle-the thermohydraulic generation of strong pressure (sound) pulses-is reported which promises a considerably extended lifetime. The energy efficiency is comparable to that of commercial shockwave sources based on the magnetodynamic principle. The underlying physics is that of the generation of strong thermoelastic waves in electrically conducting media, in particular in electrolytes, by direct ohmic heating with intense current pulses. A simplified model is discussed to describe the pressure amplitudes and the influence of the thermoacoustic properties of the electrolyte. The source is scalable over a large range, and is arbitrarily adaptable in its shape. Large-area plane waves with amplitudes of up to 5 MPa have been achieved, as well as a self-focusing geometry with peak pressures of over 70 MPa.