HR: 1340h
AN: SH23A-1164    [Abstracts]
TI: Eigenmode Structure in Solar Wind Langmuir Waves
AU: * Malaspina, D M
EM: David.Malaspina@colorado.edu
AF: University of Colorado, Laboratory for Atmospheric and Space Physics, Univ Colorado LASP 1234 Innovation Dr, Boulder, CO 80303, United States
AU: Ergun, R
EM: ree@lasp.colorado.edu
AF: University of Colorado, Laboratory for Atmospheric and Space Physics, Univ Colorado LASP 1234 Innovation Dr, Boulder, CO 80303, United States
AU: Bougeret, J
EM: jean-louis.bougeret@obspm.fr
AF: Observatoire de Paris, LESIA Observatoire de Paris 5, place Jules Janssen, Meudon, 92195, France
AU: Kaiser, M L
EM: michael.l.kaiser@nasa.gov
AF: NASA Goddard Space Flight Center, NASA Goddard SFC MC 674, Greenbelt, MD 20771-0001, United States
AU: Bale, S
EM: bale@ssl.berkeley.edu
AF: University of California Berkeley, Space Science Laboratory, Univ Calif Berkeley Space Science Laboratory Centennial Dr, Berkeley, CA 94720-7450, United States
AU: Cairns, I H
EM: i.cairns@physics.usyd.edu.au
AF: University of Sydney, University of Sydney School of Physics Physics Road, Sydney, NSW 2006, Australia
AU: Cattell, C A
EM: cattell@fields.space.umn.edu
AF: University of Minnesota, Univ Minnesota Tate Lab Physics 116 Church St SE, Minneapolis, MN 55455, United States
AU: Kellogg, P J
EM: kellogg@waves.space.umn.edu
AF: University of Minnesota, Univ Minnesota Tate Lab Physics 116 Church St SE, Minneapolis, MN 55455, United States
AU: Newman, D L
EM: David.Newman@Colorado.EDU
AF: University of Colorado, Laboratory for Atmospheric and Space Physics, Univ Colorado LASP 1234 Innovation Dr, Boulder, CO 80303, United States
AB: Bursty Langmuir waves associated with space plasma phenomena including type II and type III solar radio bursts, auroral field-aligned electrons, and radiation from shocks often exhibit localized beat-type waveforms. A consensus view on the modulation mechanism remains elusive. Current theories include multi-wave interactions, turbulence, or non-linear growth such as kinetic localization. Most of these theories start with the assumption that the density of the background plasma is near-uniform, in spite of numerous observations to the contrary. An alternative approach is to start with the assumption that density perturbations pre-exist. We construct an analytical electric field solution, describing Langmuir waves as a combination of trapped eigenmodes within a parabolic density well. This hypothesis is supported by discreet frequency structure in auroral Langmuir wave observations observed to be associated with density fluctuations, and by the high degree of localization observed in solar wind borne Langmuir waves. This simple, one-dimensional model can reproduce waveform and frequency structure of localized Langmuir waves observed by STEREO/SWAVES. The waveforms can be reasonably reproduced using linear combinations of only a few low-mode eigenmode solutions. The eigenmode solutions are sensitive to plasma environmental parameters such as the electron temperature and solar wind velocity. The trapped-eigenmode solutions can form a theoretical basis to explore the non-linear behavior of Langmuir waves which may allow for efficient conversion and escape of electromagnetic emissions and second harmonic production.
DE: 7800 SPACE PLASMA PHYSICS
DE: 7867 Wave/particle interactions (2483, 6984)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting