The effect of acceleration on single bubble Sonoluminescence (SBSL) is studied on the NASA KC-135 aircraft during a series of low-gravity and hypergravity (1.8g) portions of the flight. A bubble is trapped at the center of a spherical glass resonator filled with degassed water and driven at 32 kHz. Simultaneous strobed video, light output, sound level, and acceleration measurements are made in addition to measurements of several environmental parameters. Light output is typically seen to increase during the low gravity portions of the flight. Digital image analysis of the video record shows that the maximum bubble radius also increases during the low-gravity periods. By fitting the Rayleigh-Plesset equation to the radius-time record from video, one can infer that the ratio of acoustic pressure to ambient pressure increases during low gravity, as does the average bubble radius. Either a decrease in hydrostatic pressure in the cell or a slight shift of the bubble toward the pressure antinode during low gravity could effect this kind of change in the pressure ratio. In related research, bubbles in the laboratory were trapped without a sound field by the optical radiation pressure of light generated by a solid-state laser system.
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