PHASE-INVERTING PARABOLIC CONCENTRATOR FOR THE GENERATION OF NEGATIVEWAVES IN WATER

A method of generating very strong focused negative pressure fields in water for cavitation studies from shock waves produced by an electrom agnetic transducer is described. By using a reflecting concentrator wi th a phase-inverting central element, focal pressures of around -16 MP a from a +5-MPa source have been measured. The combination of an elect romagnetic transducer and a phase-inverting parabolic concentrator pro vides a reliable and reproducible source of cavitation bubbles for stu dy. A qualitative study of the cavitation field produced by the device , using a laser schlieren technique, is presented. (C) 1997 Acoustical Society of America.