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Time evolution from linear to nonlinear stages in magnetohydrodynamic parametric instabilities

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TLDR
In this article, the nonlinear evolution of the magnetohydrodynamic (MHD) parametric instability of wave fluctuations propagating along an unperturbed magnetic field is investigated.
Abstract
The nonlinear evolution of the magnetohydrodynamic (MHD) parametric instability of wave fluctuations propagating along an unperturbed magnetic field is investigated. Both a magnetohydrodynamic perturbation‐theoretical approach and a nonlinear MHD simulation are used. It is shown that high harmonic waves are rapidly excited by wave–wave coupling, and that the wave spectrum evolves from a state containing a small number of degrees of freedom in k space to one which contains a large number of degrees of freedom. It is found that the spectral evolution prior to nonlinear saturation is well described by the perturbation theory. During this stage, the ratio of the growth rate of the nth harmonic wave to the linear growth rate of the fundamental wave is n. The nonlinear saturation stage is characterized by a frequency shift of the fundamental wave that destroys the wave–wave resonance condition which, in turn, causes the wave amplitude to cease its growth.

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Citations
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The Solar Wind as a Turbulence Laboratory

TL;DR: In this paper, the authors focus on a topic of fundamental importance for both plasma physics and astrophysics, namely the occurrence of large-amplitude low-frequency fluctuations of the fields that describe the plasma state.
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Parametric decay of circularly polarized Alfvén waves: Multidimensional simulations in periodic and open domains

TL;DR: In this article, the nonlinear evolution of monochromatic large-amplitude circularly polarized Alfven waves subject to the decay instability was studied via numerical simulations in one, two, and three spatial dimensions.
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Beat, modulational, and decay instabilities of a circularly polarized Alfven wave

TL;DR: In this paper, the authors presented a series of new analytical approximations to the dispersion relation of a circulary polarized low-frequency electomagnetic pump wave propoagating along an ambient magnetic field.
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Simulation study of the role of ion kinetics in low‐ frequency wave train evolution

TL;DR: In this paper, it was shown that moderate amplitude (delta B/B less than 1/2) wave trains give instabilities and saturated states which differ completely from pure fluid evolution.
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Parametric instabilities of circularly polarized large-amplitude dispersive Alfvén waves: excitation of obliquely-propagating daughter and side-band waves

TL;DR: In this paper, the decay and modulational instabilities of a large-amplitude circularly polarized dispersive parallel-propagating Alfven wave were derived for arbitrary propagation angles.
References
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Book

Spectral Methods in Fluid Dynamics

TL;DR: Spectral methods have been widely used in simulation of stability, transition, and turbulence as discussed by the authors, and their applications to both compressible and incompressible flows, to viscous as well as inviscid flows, and also to chemically reacting flows are surveyed.
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On the modulational instability of hydromagnetic waves parallel to the magnetic field

TL;DR: In this paper, the stability of circularly polarized waves of finite amplitude propagating parallel to the magnetic field is studied. And the authors show that finite amplitude always promotes stability, while amplitude dependent stability conditions for long waves, previously obtained by the author, are confirmed.
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Weak Non-Linear Hydromagnetic Waves in a Cold Collision-Free Plasma

TL;DR: In this article, the system of equations for the magneto-acoustic wave propagating along a critical direction is reduced to a simple dispersive equation similar to the Korteweg-de Vries equation except that the third order derivative (the dispersion term) is replaced by the fifth order one.
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Decay instability of finite-amplitude circularly polarized Alfven waves - A numerical simulation of stimulated Brillouin scattering

TL;DR: In this paper, an energy transfer from the parent wave to two daughter Alfven-like waves and a sound-like wave is observed (a stimulated Brillouin scattering process), and the observed growth rates and propagation characteristics of these daughter waves agree with the analytical results.
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