Initial growth of sonochemically active and sonoluminescence bubbles at various frequencies

The initial growth of acoustic cavitation activity is important in some applications such as therapeutic and diagnostic medicine. The initial growth of cavitation activity has been investigated using sonoluminescence and sonochemical activity (sonochemiluminescence) at 358 kHz, 647 kHz and 1062 kHz and at 5 W, 15 W and 30 W applied power levels. The growth of sonochemically active bubble population is found to be much faster than that of sonoluminescence bubble population at 358 kHz and 647 kHz whereas almost similar growth rate is observed at 1062 kHz for both bubble populations. This suggests that the cavitation bubble resonance size ranges of sonoluminescence and sonochemically active bubbles are different at 358 kHz and 647 kHz, whereas they have similar size range at 1062 kHz. At 358 kHz and 647 kHz, relatively smaller bubbles become chemically active. Possible reasons for such observations have been discussed. The data presented and discussed in this study may be useful in controlling the growth of cavitation bubble population in addition to enhancing the knowledge base in cavitation science.