Phase interdiction mode'S theoretical model for difference frequency wave of a nonlinear sound radiator

Within the framework of known analytical solutions of Khohlov-Zabolotskaja-Kuznetsov equation the theoretical model of a nonlinear acoustic radiator with a three-frequency pump wave for 1-st harmonic of difference frequency wave is considered taking into account dissipative and diffraction processes in Gauss beam. Representing in the second approach a difference frequency wave as superposition of two synchronously and collinear spreading components with equal frequencies, it is shown, that its spatial and amplitude-phase characteristics besides amplitude-phase relations in a pump spectrum essentially depend on diffraction changes of amplitudes and phases of primary waves. Most obviously this dependence is shown in a phase interdiction mode, when with special selection of amplitude and phase pump spectra, generation of difference frequency wave in the media is practically completely stopped (is forbidden). Numerical analyze results of theoretical model for conditions of fresh water are well agreed with the data of experimental researches. The area of practical use of the study includes high-sensitivity media spottiness diagnostics, detection of objects near to medium borders, reduction of nonlinear attenuation, etc.