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Ann. Geophys., 22, 2171-2179, 2004
www.ann-geophys.net/22/2171/2004/
© European Geosciences Union 2004
Resonant three-wave interaction in the presence of suprathermal electron fluxes
C. Krafft1 and A. Volokitin2
1Laboratoire de Physique des Gaz et des Plasmas, Université Paris Sud, 91405 Orsay Cedex, France
2Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation, Academy of Sciences, Troitsk, Moscow Region, 142190, Russia
Abstract. A theoretical and numerical model is presented which describes the nonlinear
interaction of lower hybrid waves with a non-equilibrium electron
distribution function in a magnetized plasma. The paper presents some
relevant examples of numerical simulations which show the nonlinear
evolution of a set of three waves interacting at various resonance
velocities with a flux of electrons presenting some anisotropy in the
parallel velocity distribution (suprathermal tail); in particular, the case
when the interactions between the waves are neglected (for sufficiently
small waves' amplitudes) is compared to the case when the three waves follow
a resonant decay process. A competition between excitation (due to the fan
instability with tail electrons or to the bump-in-tail instability at the
Landau resonances) and damping processes (involving bulk electrons at the
Landau resonances) takes place for each wave, depending on the strength of
the wave-wave coupling, on the linear growth rates of the waves and on the
modifications of the particles' distribution resulting from the linear and
nonlinear wave-particle interactions. It is shown that the energy carried by
the suprathermal electron tail is more effectively transfered to lower
energy electrons in the presence of wave-wave interactions.
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