Surface-wave instabilities, period doubling, and an approximate universal boundary of bubble stability at the upper threshold of sonoluminescence

Numerical results are presented for hydrodynamic instabilities surrounding the parameter space of sonoluminescing bubbles. The Rayleigh-Taylor instability is shown to limit bubble oscillations only in a small region near a border at small radii in noisy environments. Also, two different noise-induced instabilities by secondary collapses are identified. The reason for period-doubled, anisotropic emission is found to be the coupling of radial and surface oscillations. Furthermore, an approximate universal border is shown to exist above which the bubble is destroyed by the parametric instability. The results are compared to experimental results from several publications using different experimental setups.