Physical Processes Related to Discharges in Planetary Atmospheres

Abstract

This paper focuses on the rudimentary principles of discharge physics. The kinetic theory of electron transport in gases relevant to planetary atmospheres is examined and results of detailed Boltzmann kinetic calculations are presented for a range of applied electric fields. Comparisons against experimental swarm data are made. Both conventional breakdown and runaway breakdown are covered in detail. The phenomena of transient luminous events (TLEs), particularly sprites, and terrestrial gamma-ray flashes (TGFs) are discussed briefly as examples of discharges that occur in the terrestrial environment. The observations of terrestrial lightning that exist across the electromagnetic spectrum and presented throughout this volume fit well with the broader understanding of discharge physics that we present in this paper. We hope that this material provides the foundation on which explorations in search of discharge processes on other planets can be based and previous evidence confirmed or refuted.R. Roussel-Dupré ( ) · J.J. Colman · E. Symbalisty

HYDROFLASH: A 2-D Nuclear EMP Code Founded on Finite Volume Techniques

“…5-7. Future plans for enhancing HYDROFLASH include: 1) incorporating the neutron output of the device and neutron transport, 2) adding the energetic X-ray output, 3) solving the full Boltzmann equation for electron transport with finite volume techniques as described in [35], [28]- [29], 4) solving the time-dependent radiation transport equations for gamma rays [36], 5) incorporating additional materials relevant to an urban environment, and 6) developing non-uniform meshes to accommodate sharp boundaries throughout the grid.…”

“…the integral of S γ over time is equal to 1, units of S γ are MeV/s), ν E is the energy loss rate of for Compton electrons, � � is the Compton electron total speed, F D is the dynamical friction force for energetic electrons in air [28], ε c is the Compton electron energy, u 0 and v 0 are the radial and theta speeds with which Compton electrons are born, ν s is the scattering rate of Compton electrons in air, e is the charge of an electron, z (= 7.2) is the mean atomic charge of air and D (= 8.078x10 19 ) is a normalization constant to accommodate MKS units. MKS is used throughout the formulation of HYDROFLASH.…”

“…(4) is retained. The drift speed, characteristic energy, ionization rate (secondary electrons producing additional secondary electrons), and attachment rate as a function of electric field strength are derived from "swarm" measurements [28]- [29]. The source and loss terms in Eq.…”

“…Eqs. (26)- (28) can be solved using standard finite volume techniques for hyperbolic equations as described in [28], see pp. 424-434 for the acoustics problem in two dimensions.…”

Experimental simulation of satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds

“…The resulting energetic electrons are accelerated by the electric fields following an intense lightning discharge and develop into a quickly growing non-linear electron avalanche process (Gurevich et al, 2004(Gurevich et al, , 2003(Gurevich et al, , 2002. The primary electrons can reach relativistic energies with a mean of ∼7 MeV and a standard deviation of ∼6 MeV (Roussel-Durpé et al, 2008) prior to escaping into near-Earth space (Inan, 2005;Lehtinen et al, 2000Lehtinen et al, , 1996. It is indeed possible to observe terrestrial relativistic electrons in space with particle detectors on satellites (Carlson et al, 2009;Dwyer et al, 2008;Feldman et al, 1996Feldman et al, , 1995Burke et al, 1992), but the direct association with individual intense lightning discharges remains to be made.…”