Shape and extinction thresholds in sonoluminescence parameter space

Experimental single bubble sonoluminescence (SBSL) ambient radius, acoustic drive pressure (Ro−Pa) phase diagrams are compared with predictions of the Dissociation Hypothesis (DH) and calculations of the n=2,3,4 shape thresholds, focusing on the location of unstable SBSL and the extinction threshold. A phase diagram for experimental runs with a 20% air saturation is shown to indicate the location of the SBSL extinction threshold. Mixtures with appropriate concentrations of argon and nitrogen are presented to show the location of unstable SBSL. The results are consistent with the DH and show that unstable SBSL and the extinction threshold appear to coincide more closely with the n=4 shape threshold.