Trapped Bubble Dynamics in Cryogenic Fluids

Initial studies of the properties of helium bubbles acoustically trapped in liquid nitrogen at 66 K have been carried out. Laser scattering is used to monitor the dynamics of the bubble radius as a function of the acoustic driving field. In this apparatus, no sonoluminescence has yet been observed from helium bubbles in liquid nitrogen, although sonoluminescence was previously observed from xenon bubbles in ethanol cooled to 165 K. It is found that bubbles can be stably trapped at quite low acoustic drive levels, enabling the observation of new dynamical bubble behavior.