Stable nonspherical bubble collapse including period doubling in sonoluminescence.

Abstract

We present observations of stable spherical symmetry broken states in single bubble sonoluminescence including observations of period doubled states. States observed involve both spatially oriented states and states with a tumbling symmetry axis. The observations are made using a fiber based four-channel correlation scheme. The measurements are made both with and without narrow band optical filters. The symmetry broken states are seen in all cases even using a 650+/-40-nm filter. This fact may be used to distinguish between different theories for the light emission. Prior to the measurements reported here, theoretical attempts to explain observations of period doubling bifurcation phenomena in single bubble sonoluminescence were centered on radially bifurcated collapses. The present experiments show unequivocally that the observations are primarily a result of breaking the spherical symmetry in the bubble collapse. Period doubling will at most show up as secondary effects in the total light output, if at all.