Difference Frequency Radiation from a Cavitating Parametric Source

Abstract

A cavitating projector radiating two primary frequencies exhibits much higher efficiency in the generation of difference frequency energy than the conventional noncavitating parametric source. The results of experimental work using a mean primary frequency of 25 kHz demonstrate essentially omnidirectional patterns with source levels considerably higher than the on-axis levels obtained from the same source operating at the same input power at depths sufficient to prevent cavitation. The spectrum of the signal exhibits energy strongly concentrated at the difference frequency and its harmonics.