Modeling of X-ray emissions produced by stepping lightning leaders

Wei Xu (1) , Sébastien Celestin (2) , Victor P. Pasko (1)

1 CSSL - Communications and Space Sciences Laboratory [PennState]
2 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace

Intense and brief bursts of X-ray emissions have been measured during the stepping process of both natural cloud-to-ground (CG) and rocket-triggered lightning flashes. In this paper, we investigate theoretically the energy spectra of X-rays produced by the bremsstrahlung emission of thermal runaway electrons accelerated in the inhomogeneous electric field produced around lightning leader tips. The X-ray energy spectrum depends on the physical properties of the associated lightning leaders. Consequently, X-ray measurements can be used for diagnostics of the electrical properties of lightning stepped leaders. We report simulation results of the photon energy spectra produced by 5 and 10 MV negative CG lightning discharges that would be measured from the ground using ideal detectors. We also quantify theoretically the radial dependence of X-ray energy spectra received at ground level during the leader stepping process. Moreover, it is found that the ground radiation generated in this process is harmless to humans.

Domaines: Planète et Univers [physics]

Wei Xu, Sébastien Celestin, Victor P. Pasko. Modeling of X-ray emissions produced by stepping lightning leaders. Geophysical Research Letters, 2014, 41, pp.7406-7412. ⟨10.1002/2014GL061163⟩. ⟨insu-01174373⟩