Nonlinear change of on-axis pressure and intensity maxima positions and its relation with the linear focal shift effect

TL;DR

This paper investigates how nonlinear effects cause the pressure and intensity maxima in focused acoustic beams to shift differently along the axis, especially in low-Fresnel-number beams, contrasting with linear behavior.

Contribution

It provides experimental evidence and interpretation of the nonlinear separation and movement of pressure and intensity maxima in focused acoustic beams.

Findings

Pressure and intensity maxima separate in the nonlinear regime.

Maxima move differently along the axis under increasing voltage.

Effects are more pronounced in low-Fresnel-number beams.

Abstract

Experimental results related with the movement of the position of pressure and intensity maxima along the axis of focused acoustic beams under increasing driving voltages and its interpretation are presented. It is shown that in the nonlinear regime the points of the pressure and intensity maximum are separated and move differently along the axis, contrary to the linear regime, where these points coincide. The considered effects are particularly strong in the case of low-Fresnel-number beams.