Fred B. Seeley
Dept. of Phys., Univ. of Alabama, Huntsville, AL 35899
Jonathan P. Dowling
U.S. Army Missile Command, Redstone Arsenal, AL 35898-5248
Observations and measurements are reported of trains of traveling-wave pressure impulses that are coincident with the onset of stable, synchronous sonoluminescence. Each pressure impulse is initiated by a hard collapse of the centered bubble, travels outward to the flask boundary, is reflected, and then reconverges. The converging impulse apparently rebounds from the free boundary of the bubble and the impulse continues traveling outward and inward until it is synchronized with a subsequent collapse. It is hypothesized that synchronous sonoluminescence is produced when this train of spherically symmetric, concentric pressure traveling impulses are synchronized with the driving standing wave. Experimental observations of integral numbers of such impulses for a number of spherical flasks at several harmonics support this hypothesis. Theoretical analyses of these experimental observations and measurements will be presented.