Optimal resonant stimulation of sonoluminescence

Abstract

In single-bubble sonoluminescence, a bubble is levitated and forced to oscillate by a standing sound wave. Once per cycle, at the maximum compression of the bubble volume, the emission of a pulse of visible light is observed; due to the strong bubble collapse, a shock wave is emitted in the liquid also. It was found that these shock waves can be visualized by the means of a schlieren method. Using a stroboscopic illumination of the bubble, its dynamical behavior and the shocks can be recorded in slow motion by a video camera. Experimentally measured velocities of the shock waves were compared with numerical calculations. Further, the recorded shock waves contain information about the bubble position and collapse time. In the regime of instable sonoluminescence, sudden changes in bubble position depending on bubble size were observed. The phenomenon in the context of interactions of the bubble with the complex sound field is discussed. [Work supported by the DFG (SFB 185).]