Characteristics of acoustic response from simulated impulsive lightning current discharge

Abstract

Acoustic observation of laboratory simulated lightning discharge can greatly avoid the observation difficulties under natural thunderstorm environment. An acoustic observation experiment based on the impulsive current generation system and a microphone array was carried out and illustrated in this study. A quantitative study on characteristics of response sound pressure initiated from simulated lightning current was performed. The first arrived acoustic N-waves measured at different distances initiated from different discharge amplitudes were compared and analysed. The acoustic amplitude, rise time and duration time defined for N-waves and peak frequencies were found to have an obvious correlation with the discharging amplitudes of simulated lightning currents and the observing distances. The linear change of acoustic amplitude is more obvious than that of the other parameters with the changed discharging amplitude or observing distance. A certain degree of shape change of the simulated lightning current except for the amplitude may not significantly affect the response acoustic characteristics when comparing the first acoustic N-waves from 8/20 μs lightning current and another kind of impulsive current which has a wider shape and two subsequent peaks. The subsequent current peaks in short time delays were proved to successively generate acoustic N-waves independently without overlapping, which meanwhile, indicated a consistent linear relationship of amplitude and time delay between electrical and acoustic pulses.