An Attempt to Produce Electrical Discharges in Acoustic Cavitation Bubbles

抄録

It is widely known that cavitation bubbles are not static bubbles but have the dynamics of the expansion, the shrinkage, and the collapse. In this work, we produced electrical discharges in acoustic cavitation bubbles for the first time with the intension of enhancing the reactivity of sonochemical processes. Glow-like discharges were observed in cavitation bubbles on the bottom surface of the cylindrical electrode which was connected to a pulsed high-voltage power supply. Bright optical emission was observed from the region corresponding to the cloud of expanded cavitation bubbles, while we also observed electrical discharges even in the shrinking phase of cavitation bubbles. If discharge-produced reactive species have lifetimes that are longer than the interval between the discharge and the collapse of the cavitation bubble, the species composition in the collapsed cavitation bubble becomes different from that in conventional cavitation bubble, which may result in the enhancement of reactivity in sonochemical processes.