HR: 0830h
AN: SM21B-0217    [PDF]
TI: Linear Property and Nonlinear Evolution of Buneman Instability
AU: * Omura, Y
EM: omura@kurasc.kyoto-u.ac.jp
AF: RASC, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Ninomiya, K
EM: ninomiya@kurasc.kyoto-u.ac.jp
AF: RASC, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Umeda, T
EM: umeda@kurasc.kyoto-u.ac.jp
AF: RASC, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Heikkila, W J
EM: heikkila@utdallas.edu
AF: University of Texas at Dallas, Richardson, Texas, TX 75083 United States
AU: Matsumoto, H
EM: matsumot@kurasc.kyoto-u.ac.jp
AF: RASC, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AB: The Buneman instability is one of the most fundamental instabilities that arise along the magnetic field line, when thermal electrons are accelerated by an external electric field along the ambient magnetic field. Such electric fields are induced, when the magnetosphere undergoes dynamic changes of its structure such as magnetic reconnection or reconfiguration. We first assume a stable plasma with thermal electrons and ions at rest, where the thermal electrons and ions can have different temperatures as specified by the thermal velocities Ve and Vi, respectively. Under the electric field imposed along the magnetic field, the thermal electrons are accelerated to a finite drift velocity Vd relative to the thermal ions. When the Vd exceeds a critical value, the Buneman instability sets in to convert the drift kinetic energy to electrostatic field energy and thermal energies of electrons and ions. As the electrostatic field grows the electrons are rapidly diffused through nonlinear trapping motion. We first present a series of linear dispersion analyses of the Buneman instability for various combination of Ve/Vd and Vi/Vd. We then performed particle simulations starting with a finite drift velocity Vd and with various initial thermal velocities Ve/Vd and Vi/Vd. The nonlinear evolutions of the instability result in a variety of electrostatic potential structures along the magnetic field line such as electron holes, ion holes, ion acoustic waves and double layers. The final state of the nonlinear evolution also depends on whether the system is uniform with periodic boundaries or nonuniform with open boundaries.
DE: 7815 Electrostatic structures
DE: 7835 Magnetic reconnection
DE: 7839 Nonlinear phenomena
DE: 7843 Numerical simulation studies
DE: 7867 Wave/particle interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting