LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS

Journal Article · Thu Aug 20 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/809/2/176· OSTI ID:22525545

Krafft, C. ^[1]; Volokitin, A. S. ^[2]

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1. Laboratoire de Physique des Plasmas, Ecole Polytechnique, F-91128 Palaiseau Cedex (France)
2. IZMIRAN, Troitsk, 142190, Moscow (Russian Federation)

Langmuir turbulence excited by electron flows in solar wind plasmas is studied on the basis of numerical simulations. In particular, nonlinear wave decay processes involving ion-sound (IS) waves are considered in order to understand their dependence on external long-wavelength plasma density fluctuations. In the presence of inhomogeneities, it is shown that the decay processes are localized in space and, due to the differences between the group velocities of Langmuir and IS waves, their duration is limited so that a full nonlinear saturation cannot be achieved. The reflection and the scattering of Langmuir wave packets on the ambient and randomly varying density fluctuations lead to crucial effects impacting the development of the IS wave spectrum. Notably, beatings between forward propagating Langmuir waves and reflected ones result in the parametric generation of waves of noticeable amplitudes and in the amplification of IS waves. These processes, repeated at different space locations, form a series of cascades of wave energy transfer, similar to those studied in the frame of weak turbulence theory. The dynamics of such a cascading mechanism and its influence on the acceleration of the most energetic part of the electron beam are studied. Finally, the role of the decay processes in the shaping of the profiles of the Langmuir wave packets is discussed, and the waveforms calculated are compared with those observed recently on board the spacecraft Solar TErrestrial RElations Observatory and WIND.

• OSTI ID: 22525545
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 809; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
ENERGY TRANSFER
FLUCTUATIONS
IONS
NONLINEAR PROBLEMS
PLASMA DENSITY
PLASMA SIMULATION
SOLAR ELECTRONS
SOLAR WIND
SOUND WAVES
SPACE
SPACE VEHICLES
SUN
TURBULENCE
WAVE FORMS
WAVE PACKETS