Electroacoustic characteristics of repetitive spark discharge and its interaction with induced flow fields

This study explores the electroacoustic characteristics of needle-to-needle electrode repetitive spark discharges by capturing and analyzing the time-domain waveforms of electroacoustic signals throughout the discharge process. The effects of varying pulse frequencies, electrode gap distances, pulse widths and microphone placement distances on acoustic waves were carefully investigated. Results indicate that the main frequency amplitude of the discharge acoustics shows a trend of decreasing initially and then increasing with the increase of pulse repetition frequency, while the ratio of the acoustic main frequency to the pulse modulation frequency first increases and then decreases. Additionally, variations in electrode gap distances and pulse widths can influence the discharge mode and energy, leading to significant changes in the discharge acoustic characteristics. Using simplified Particle Image Velocimetry (PIV) technology, we observed that these changes in electroacoustic discharge are directly related to the spatial flow field induced by repetitive spark discharges. The results demonstrate that the electroacoustic characteristics of discharges can effectively reflect changes in plasma parameters that are otherwise difficult to detect. This suggests that in certain aspects, discharge acoustics can serve as an excellent diagnostic tool for plasma.