HR: 10:20h
AN: AE12A-01 INVITED     [Abstracts]
TI: Some Numerical ExperimentsRelating to Step Leaders and Return Strokes
AU: * Zinn, J
EM: jzinn@lanl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 United States
AB: In this talk we discuss two separate computer models intended to relate to lightning discharges. Model 1 treats the radiative and hydrodynamic expansion of the return stroke channel and its chemical evolution, including visible light emission, nitrogen oxide production and the hydrodynamic shock (thunder). We derive estimates of the NOx production per unit energy of the discharge and discuss the chemical reaction sequences that are involved, including the role of diffusion in the freeze-out of non-equilibrium NOx concentrations. The second model is our first step in attempts to describe the step leader. It treats the propagation of an ionization front starting from a local region where the E field intensity exceeds the Townsend breakdown threshold. The model starts with mathematical fits to measurements of electron reaction rate parameters, effective electron energies and electron drift velocities, as functions of E/N. Results include plots of the evolution of charge density wave structures and the associated E field distributions.
DE: 0545 Modeling (4255)
SC: Atmospheric and Space Electricity [AE]
MN: Fall Meeting 2005