Laser-induced shock inside a cylindrical water column

Abstract

An investigation of laser-induced shock inside a water column is conducted. We focus on the reflection of the shock by the circle interface and discuss the dynamics of the wavefront at the different initial locations of the shock. Based on the approximation of linear geometrical acoustics, the wavefront is determined by a parametric equation, and the results agree well with our experiment. It is found that the dominant characteristic is the cusps (singularity), which is attributed to the caustics of the circle interface, and a singularity on the loci of the cusps indicates a more complex wavefront than a plane wave incident to a water column. In addition, the reflected wave-induced cavitation is observed, which is closer to the interface as the initial breakdown regions move away from the column center. Because of the circular interface, our wavefront dynamics results also provide a better understanding of an internal shock inside a spherical drop.