HR: 0800h
AN: SH31A-1174    [Abstracts]
TI: Linear Beam-Plasma Instabilities in the Presence of Finite Amplitude Backward Propagating Waves
AU: * Hoyos, J H
EM: jhoyos@fisica.ciencias.uchile.cl
AF: Universidad de Chile, Facultad de Ciencias, Dep. de Fisica, Las Palmeras 3425, Nunoa, Santiago, 1 Chile
AU: Gomberoff, L
EM: lgombero@uchile.cl
AF: Universidad de Chile, Facultad de Ciencias, Dep. de Fisica, Las Palmeras 3425, Nunoa, Santiago, 1 Chile
AB: In previous works finite amplitude circularly polarized waves propagating forward relative to the background magnetic field were shown to affect the behavior of linear proton beam-plasma instabilities [1-4]. We now study the behavior of these instabilities in the presence of finite amplitude circularly polarized backward propagating waves. We find that the presence of both right-hand and left-hand polarized backward propagating waves stabilize linear beam-plasma right-hand instabilities when their amplitude is above a treshold value. It has been shown than forward propagating waves can stabilize right-hand instabilities [1-3]. Here we show that the threshold wave amplitude required to stabilize the right-hand instabilty is larger for forward propagating waves than the amplitude threshold for backward propagating waves. Thus, backward propagating waves can be in some physical conditions a more efficient mechanism to stabilize linear right-hand instabilities. Also we find that the presence backward propagating waves can produce electrostatic instabilities by making the phase velocities of the linear ion acoustic waves become equal above a treshold amplitude value. These results can be relevant in various space plasma enviroments. \vspace{12pt} \parindent=0pt {\bf References} [1] L. Gomberoff, Stabilization of linear ion beam right-hand polarized instabilities by nonlinear Alfv‚n/ion-cyclotron waves, {\em J.Geophys.Res.}, 108 (A6), 1261, doi: 10.1029/2003JA009387, 2003. [2] L. Gomberoff, J. Hoyos, and A. L. Brinca, Effect of a large amplitude circularly polarized wave on linear beam-plasma electromagnetic instabilities, {\em J. Geophys. Res.}, 108 (A12), 1472, doi: 10.1029/2003JA010144, 2003. [3] J. Araneda and L. Gomberoff, Stabilization of right-hand beam plasma instabilities due to a large amplitude left-hand polarized wave: A simulation study, {\em J. Geophys. Res.}, 109, A01106, doi: 10.1029/2003JA010189, 2003. [4] L. Gomberoff, J. Hoyos, A. L. Brinca and R. Ferrer, Electrostatic instabilities induced by large amplitude left-hand polarized waves, {\em J. Geophys. Res.}, 109, A07108, doi:10.1029/2004JA 010466, 2004.
DE: 7839 Nonlinear phenomena
DE: 7867 Wave/particle interactions
DE: 7868 Wave/wave interactions
DE: 7871 Waves and instabilities
DE: 0689 Wave propagation (4275)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting