Abstract:
Femtosecond pulsed Mie scattering and a needle hydrophone have been used to probe the behavior of a light-emitting bubble near that moment when the stress of implosion is at a maximum. It is found that the wall of the bubble is collapsing with a velocity over four times the ambient speed of sound in the gas. The deceleration at the minimum is over 10[sup 11] g. The improved timing resolution afforded by this arrangement localizes the flash to within 500 ps of the minimum. The collapsing bubble launches a strong pulse into the surrounding water with a rise time shorter than 10 ns. [Work supported by the NSF.]