HR: 0800h
AN: AE31A-0159    [Abstracts]
TI: First Principles Calculations of Excitation Rates in the Presence of an Electric Field
AU: * Colman, J J
EM: jonah@lanl.gov
AF: Los Alamos National Laboratory, EES-2, MS D401, Los Alamos, NM 87545 United States
AU: Roussel-Dupr‚, R
EM: rroussel-dupre@lanl.gov
AF: Los Alamos National Laboratory, EES-2, MS D401, Los Alamos, NM 87545 United States
AU: Triplett, L
EM: ltriplet@lanl.gov
AF: Los Alamos National Laboratory, EES-2, MS D401, Los Alamos, NM 87545 United States
AU: Travis, B
EM: bjtravis@lanl.gov
AF: Los Alamos National Laboratory, EES-2, MS D401, Los Alamos, NM 87545 United States
AB: In this paper we describe detailed 4.5 dimensional (two spatial dimensions and 2.5 phase space dimensions) kinetic calculations for the electron distribution function resulting from the injection of energetic electrons into air. Various pressures and applied electric field intensities are investigated. From the electron distribution function and measured excitation cross-sections we then compute the optical efficiencies for a large number of nitrogen and oxygen lines across the electromagnetic spectrum from 320.0 nm to 800.0 nm. The fluorescence efficiencies used in calculating the optical emissions produced by energetic particles and penetrating radiation in air are derived for the most part from the measurements of Davidson and O'neil ({\it J. Chem. Phys.}, {\bf 41}, No. 12, 3946, 1964), Mitchell (J. Chem. Phys., 53, No. 5, 1795, 1970) and Hartman ({\it Planet. Spa. Sci.}, {\bf 16}, 1315, 1968). These efficiencies were obtained from experiments conducted at various air pressures and in the absence of an applied electric field. We choose beam parameters and dimensions that are directly relevant to the original Davidson and O'neil experiments and present comparisons to these measurements. The computed fluorescence efficiencies can be used to determine the optical emissions associated with high-altitude discharges driven by runaway air breakdown and results are discussed in a separate presentation at this meeting (Triplett {\it et al.}). Simulations are also run for the acceleration of `Thermal' electrons in the presence of an applied electric field and we have recalculated optical emission rates that are applicable to discharges dominated by conventional breakdown for comparison with Taranenko et al. ({\it GRL}, {\bf 19}, No. 18, 1815, 1992).
DE: 2419 Ion chemistry and composition (0335)
DE: 2423 Ionization mechanisms
DE: 0335 Ion chemistry of the atmosphere (2419, 2427)
SC: Atmospheric and Space Electricity [AE]
MN: 2004 AGU Fall Meeting