An innovative method of pressure measurement inside a laser-induced cavitation bubble

This study proposes a novel method for measuring the pressure inside a laser-induced cavitation bubble during its expansion. Based on Paschen's theory, which relates electrical breakdown to gas pressure, applied voltage, and electrode distance, our approach uses two electrodes to estimate the cavitation bubble pressure at different expansion stages by noting the breakdown time at varying voltages. This method offers a high temporal resolution owing to its rapid electrical discharge response. The unveiled pressure during the expansion phase was approximately 0.4 atm. This value contradicts previous reports that assumed that the minimum pressure was close to the water vapor pressure.