Collapse of laser induced bubbles and generated sound pressure waves

The self-focusing transmission , filamentation, breakdown of intense laser pulses in water, and sound pressure waves generated during breakdown become a hot topic of intense laser pulse application research. Ionization generated bubbles compress the surrounding water bodies, which produces sound pressure waves underwater. Based on the previous theory, a dynamic model is developed, in which the gas content, viscosity coefficient and the surface tension coefficient are considered. The collapse process of double bubbles is also modeled, which could be applied to calculate the bubble radius and generated sound pressure waves. These theories are amended by introducing varying factors of water characters at different temperatures. Calculation results show that the bubbles shrink more violently and generate higher sound pressure waves when water temperature is higher. For double bubbles, higher sound pressure waves will be generated when the two bubbles are closer. The minimum collapse radiuses are varying linearly along with the distances between bubbles, and the generated maximum sound pressures are monotonically increasing.