Sonoluminescence in varying acceleration environments

Abstract

In order to prepare for experiments in variable-g environments, some of the multiple effects caused by the time-varying acceleration of acoustic resonators used in bubble levitation experiments are considered. The coupled effects of the induced changes in ambient pressure (due to a changing hydrostatic head) and bubble position (due to a change in buoyant body force) were modeled. Changing the ambient pressure, while holding the acoustic pressure amplitude constant, causes changes in the radial bubble response and diffusive equilibrium requirements. Changing the bubble levitation position causes both the local acoustic pressure amplitude and gradient to change, which will again impact bubble response. If the bubble remains in a stable diffusive equilibrium, both of these effects will force the bubble’s equilibrium radius to change. By using an empirical relation for emitted sonoluminescence intensity versus bubble response, the variation of emitted light intensity as a function of the changing ambient acceleration can be predicted. The predicted results are shown to agree quantitatively with existing experimental data from other research groups. An experiment was designed and built to fly onboard a KC-135 aircraft that has been reinforced for parabolic flight maneuvers to simulate micro and hyper gravity acceleration. Thesis advisor: R. Glynn Holt Copies of this thesis may be obtained by contacting the advisor, Glynn Holt, Dept. of Aerospace and Mechanical Engineering, Boston University, 110 Cummington St., Boston, MA 02215. E-mail address: rgholt@bu.edu