Abstract
An intensified charge-couped device (CCD) camera was used to capture raw images of multibubble sonoluminescence, generated by 168 and 448 kHz ultrasound. The effect of various air and surfactant concentrations, and pulse conditions on the acoustic pressure distribution, percentage of standing wave component, the structure of the sonoluminescence activity, and speed of streaming was investigated. It was observed that the enhancement in the sonoluminescence intensity by appropriate degassing, pulsing, and addition of sodium dodecylsulfate were closely related to an expansion in the spatial distribution of sonoluminescence activity. This broadening in the spatial distribution is correlated with a high percentage of standing wave component. This effect stems from the reduction in the attenuation of the acoustic field by inhibiting the formation of large coalesced bubbles.