Evolution of a sonoluminescence bubble under a magnetic field

Abstract

Studies of sonoluminescence (SL) in magnetic fields up to 20 T have revealed a striking magnetic field dependence. The intensity of emitted light is suppressed under increasing magnetic fields and vanishes above threshold magnetic field that depends on the applied sound pressure. Further increase in the magnetic field leads to the destruction of the bubble through dissolution. At a constant magnetic field, the light intensity is found to increase roughly linearly with increasing sound pressure until the bubble disappears above a cut-off pressure which depends on the strength of the magnetic field. The cut-off pressure is found to approximately double between 0 and 20 T. Further study of the SL bubble through the measurement of the phase of the emitted radiation relative to acoustic drive shows a large increase in phase under magnetic fields. These results suggest that the bubble grows significantly in size and that there may be a substantial modification of bubble dynamics under magnetic field. The origin of the observed effects, possibly due to magnetic field-induced anisotropies in the SL bubble, will be discussed in light of our recent anisotropy studies under magnetic fields.