Sean M. Cordry
Dept. of Phys., Univ. of Mississippi, University, MS 38677
Lawrence A. Crum Ronald A. Roy
University of Washington, Seattle, WA 98105
Bubbles created via electrolysis were allowed to rise though water in a quiet acoustic levitation vessel. The sound field was then activated, forcing several bubbles to converge and coalesce near a pressure antinode. Light emission measurements were then taken with a Hamamatsu photomultiplier tube and single photon counter as a state of single bubble sonoluminescence (SBSL) evolved. The measurements reveal brief periods fluctuations in light emission intensity followed by long periods of stable (i.e., nonfluctuating) emission. The time scales for the fluctuations are on the order of half a second. Previous measurements of light emission have indicated that SBSL exhibits remarkably long-lived, stable behavior [Gaitan et al., J. Acoust. Soc. Am. 91, 3166 (1992); B. P. Barber and S. J. Putterman, Nature 352, 318 (1991)]. These measurements, however, imply a transient regime that the bubble must pass through while seeking a final position of stability. The highest light emission intensities are seen in the transient regime. These transient light emission should provide important information concerning the mechanisms through which SBSL develops its remarkable stability. Further, acoustic emissions from SBSL were observed to evolve from broadband to narrow-band noise during the transient period. These light emissions and acoustic emissions will be presented and possible correlation discussed. [Work supported by ONR.]