Relationship between a standing-wave field and a sonoluminescing field

The relationship between a sound field and a multibubble sonoluminescing field has been studied experimentally and analytically to clarify the sonochemical reaction field. The variation of each field in a rectangular glass cell filled with distilled water or a luminol solution was investigated while changing experimental conditions such as driving frequency, applied voltage to the transducer, and thickness of the cell bottom. As for the sonoluminescing field; the intensity of sonoluminescence (SL) was measured and its distribution was observed. As for the sound field, sound energy density was analyzed theoretically and sound pressure distribution was observed optically. Comparing them, it became clear that SL occurred at pressure antinodes of a standing-wave field in the cell. There are upper and lower thresholds of the sound pressure for SL to occur. This explains the amplitude dependence and spatial nonuniformity of SL in a standing-wave field.