Cavitation threshold pressure of focused ultrasound observed with sonochemiluminescence

Abstract

Spatial distribution of sonochemiluminescence (SCL) from an argon-saturated luminol solution was measured in a focused sound field at 1 MHz in a standing-wave configuration. The SCL distribution was confined to pre-focal region at acoustic powers lower than 0.9 W, and was not located at the focus but at a few mm pre-focal side at a threshold for SCL inception. The threshold pressure amplitude for SCL inception was 3.6 atm at the focus, which value was obtained with a background-oriented schlieren method. The method is based on the broadening of multiple slits due to an optical deflection caused by ultrasound, and the broadening width measured provides an acoustic pressure amplitude. A qualitative image of the focused sound field was also obtained.

Effect of intended shift in propagation direction of cavitation generation position on coagulation position in bubble-enhanced ultrasonic heating

“…Therefore, cavitation threshold pressure was investigated in order to control cavitation bubble generation. 27) In recent years, however, high-intensity energy generated through the collapse of bubbles has begun to be used in ultrasound treatments, as exemplified by histotripsy 28) and sonoporation in drug delivery systems. 29,30) Similar to this trend, the final goal of this study is to improve the efficiency of HIFU treatment by utilizing the heating enhancement effect of cavitation bubbles.…”

Dependence of reaction on vessel position, diameter, and liquid height in the sonochemical reactor with indirect irradiation

“…1) This phenomenon is termed ultrasonic cavitation. [2][3][4][5][6] Because the collapse of bubbles by ultrasound is caused by semi-adiabatic compression, a high-temperature field is generated inside the bubbles, and a chemical reaction occurs. This reaction is termed a sonochemical reaction.…”

Theoretical analysis and experimental verification of spatial coherence of acoustic cavitation noise from bubble clusters under ultrasonic horn

“…Acoustic cavitation bubbles generated by intense ultrasound in water radiate secondary ultrasound called acoustic cavitation noise owing to their volumetric oscillation. [1][2][3][4][5] In sonochemistry, which is concerned with understanding the chemical effects associated with acoustic cavitation phenomena, [6][7][8][9][10][11] acoustic cavitation noise has been attracting attention as a method for monitoring acoustic cavitation conditions, and numerous research findings have been reported. [12][13][14][15][16][17] However, reports on the explicit use of acoustic cavitation noise other than monitoring are limited.…”