Production of uniform underwater shock waves by pulsed electric discharge

Paper reports on production and characteristics of uniform underwater shock waves for medical applications. In medical field, shock waves have been successfully applied for non-invasive disintegration of kidney stone in urology, known as extracorporeal shock wave lithotripsy (ESWL). For shock wave therapies near sensitive organs, a precise and controllable shock wave source is required. A half-parabolic refractor with 20 mm opening diameter was designed and constructed as an extracorporeal shock wave source. Underwater shock waves were generated by electric discharge. A magnetic pulse compression circuit was used as energy source. Generated spherical underwater shock waves were reflected from the generator and propagated parallel. Pressure histories were measured at different stand-off distances by using a fiber optic probe hydrophone A wide range of pressure values from 10 to 45 MPa at the exit of the generator was obtained. A wide range of peak pressures from center of reflector to 5 mm was obtained. The propagation of underwater shock waves was observed with visualization using high speed camera. The visualization was used shadowgraph method. The propagation of underwater shock waves observed propagating parallel after reflected. The cavitation was not observed after underwater shock waves propagation. The present compact extracorporeal shock wave generator has appropriate characteristics for shock waves brain interaction studies and application in precise and sensitive medical procedures.