Single-bubble sonoluminescence: Acoustic emission measurements with a fiber-optic probe hydrophone

Abstract

In single-bubble sonoluminescence additionally to the short light pulses, the bubble emits in the collapse phase a sound wave which can be measured with a fiber-optic probe hydrophone [Staudenraus and Eisenmenger, Ultrasonics 31, 267 (1993)]. This type of hydrophone is an absolute ultrasonic wideband reference standard. Compared to piezoelectric hydrophones it allows measurements with higher spatial (0.1 mm) and temporal (10 ns) resolution. The intensity and the width of the emitted sound wave increase with increasing driving pressure, but vary only slightly with water temperature in contrast to the emitted light intensity. The total radiated energy of the sound wave is below 10% of the initial energy of the bubble. The results are compared with earlier measurements on transient cavitation bubbles and with new theoretical results.