Electromagnetic radiation associated with the formation of an electric breakdown in air at atmospheric pressure

Abstract

Previous experiments on the triggering mechanisms of air discharges at atmospheric pressure (surface discharge, short gap breakdowns) showed a transient arc phase characterized by a sharp current variation with constant duration of about 10 ns. The current and potential evolution in the transient arc phase, in the case of a surface discharge, are calculated using the Rompe and Weisel’s air conductivity law and a classical propagation equation. The results of this model are consistent with experimental data and give the E field value in the transient arc zone. Furthermore, the model provides the necessary source terms for calculation of the radiated field associated with the transient arc in the dipolar approximation. This calculation shows the impulsive structure of the radiated field emitted in the VHF–UHF range during the formation of the transient arc: this pulse of a rising front of several nanoseconds is similar for amplitude and spectral content to the wide-band measurements carried out on natural lightning.