Studies of the parameters of a spark discharge between an artificial charged water-aerosol cloud and the ground

The optical and current characteristics of spark discharges between a grounded electrode and a strongly charged artificial water-aerosol cloud are studied experimentally. The spectral characteristics of the discharge current are investigated using wavelet and Fourier analyses. Three main types of discharge with different final stages are revealed and investigated. It is found that the parameters of a discharge in its final stage depend substantially on the discharge trajectory and the depth to which it penetrates into the aerosol cloud. It is shown that the parameters of the most powerful type of discharge (the brightness of the discharge channel, the current growth rate in the final stage, and the penetration depth into the charged aerosol cloud) are close to the discharge parameters in the main stage of natural lightning. It is also shown that such a discharge neutralizes up to 5% of the cloud charge. In contrast to Fourier analysis, wavelet analysis shows that the signal amplitude (i.e., the energy deposition rate in the discharge channel) is maximum at high frequencies for all types of discharge. Of special interest is the most powerful type of discharge, in which the signal amplitude (which is one to two orders of magnitude larger than in other discharges) is maximum at frequencies of several hundred megahertz.