scholarly journals Isotropic pressure model in the presence of coarse-graining scale Alfvén waves and its consequence for modulational instability

2017 ◽  
Vol 24 (9) ◽  
pp. 092903
Author(s):  
Y. Nariyuki
Keyword(s):  
Modulational Instability ◽  
Coarse Graining ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Isotropic Pressure

scholarly journals Kinetic modulational instability of broadband dispersive Alfvén waves in plasmas

2007 ◽  
Vol 73 (2) ◽  
pp. 153-157 ◽  
Author(s):  
P.K. SHUKLA ◽  
NITIN SHUKLA ◽  
L. STENFLO
Keyword(s):  
Modulational Instability ◽  
Random Phase ◽  
Alfven Waves ◽  
Nonlinear Propagation ◽  
Alfvén Waves ◽  
Nonlinear Dispersion Relation ◽  
Laboratory Plasmas ◽  
Interstellar Media ◽  
Bow Shocks ◽  
Instability Growth

Abstract.We consider a kinetic modulational instability of broadband (random phase) magnetic-field-aligned circularly polarized dispersive Alfvén waves in plasmas. By treating random phase Alfvén waves as quasi-particles, we consider their nonlinear interactions with ion quasi-modes within the framework of the wave-kinetic and Vlasov descriptions. A nonlinear dispersion relation governing such interactions is derived and analyzed. An explicit expression for the kinetic modulational instability growth rate is presented. Our results can be of relevance to the nonlinear propagation of incoherent Alfvén waves, which have been frequently observed in interstellar media, in the solar corona and in the solar wind, as well as in the foreshock regions of planetary bow-shocks and laboratory plasmas.

A note on the modulational instability of long Alfvén waves parallel to the magnetic field

1978 ◽  
Vol 19 (3) ◽  
pp. 437-447 ◽  
Author(s):  
Einar Mjølhus
Keyword(s):  
Magnetic Field ◽  
Inverse Scattering ◽  
Modulational Instability ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Stable Case ◽  
Unstable Case ◽  
Modulational Stability ◽  
Limiting Case ◽  
The Magnetic Field

An amplitude dependent criterion for modulational stability of long Alfvén waves parallel to the magnetic field is interpreted in terms of a recently obtained inverse scattering solution to the modified nonlinear Schrödinger equation. It is found that the solitons formed are of two types. In the strongly unstable case, normal solitons are formed. In the transition region of weakly unstable and stable cases, the anomalous type, which in a limiting case becomes the algebraic soliton, dominates. In the strongly stable case, no solitons are formed.

Self-interaction of Alfvén waves in a cylindrical waveguide filled with an ideally conducting compressible plasma

1991 ◽  
Vol 45 (1) ◽  
pp. 89-101
Author(s):  
Nagendra Kumar ◽  
Krishna M. Srivastava
Keyword(s):  
Compressible Fluid ◽  
Nonlinear Evolution ◽  
Modulational Instability ◽  
Alfven Waves ◽  
Cylindrical Waveguide ◽  
Radial Mode ◽  
Alfvén Waves ◽  
Nonlinear Behaviour ◽  
Compressible Plasma ◽  
Dependent Frequency

The nonlinear behaviour of azimuthally symmetric Alfvén waves propagating along the axis of a cylindrical ideally conducting compressible fluid-filled waveguide is investigated. It is shown that the nonlinear evolution of such waves is governed by the nonlinear Schrödinger equation. Modulational instability for fundamental (m = 1) radial mode is discussed for α2 = 0·1,0·2, 0·3 and different values of k. The amplitude-dependent frequency and wavenumber shifts are calculated and their variations with wavenumber are shown graphically.

scholarly journals Formation of lower-hybrid solitary structures by modulational interaction between lower-hybrid and dispersive Alfvén waves

2009 ◽  
Vol 27 (3) ◽  
pp. 1027-1033 ◽  
Author(s):  
J. O. Hall ◽  
G. Stenberg ◽  
A. I. Eriksson ◽  
M. André
Keyword(s):  
Numerical Solutions ◽  
Modulational Instability ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Lower Hybrid ◽  
Plasma Parameters ◽  
Thermal Electron ◽  
Cavity Collapse ◽  
Solitary Structures ◽  
Modulational Interaction

Abstract. We investigate the possibility that lower-hybrid solitary structures (LHSS), which are frequently observed in the Earth's ionosphere and magnetosphere, are formed as a result of a modulational interaction between lower-hybrid and dispersive Alfvén waves of initially small amplitude. A large amplitude lower-hybrid pump wave can excite density structures with length scales transverse to the geomagnetic field of the order of the ion gyroradius via a modulational instability. The structure formation in the nonlinear stage of the instability is investigated by numerical solutions of the governing equations, using plasma parameters relevant for LHSS observations in the upper ionosphere and in the magnetosphere. The numerical solutions reveal that the lower-hybrid waves become self-localized inside cylindrically symmetric (with respect to the ambient magnetic field) density cavities, in qualitative agreement with observations. Our model includes thermal electron effects but shows no stabilization at the ion sound gyroradius, suggesting that any preference of observed LHSS for that perpendicular scale likely is due to processes arresting the cavity collapse.

Nonlinear interaction of obliquely propagating Alfvén waves and kinetic Alfvén waves in solar wind plasmas

2013 ◽  
Vol 79 (5) ◽  
pp. 927-931 ◽  
Author(s):  
NITIN YADAV ◽  
R. P. SHARMA
Keyword(s):  
Solar Wind ◽  
Nonlinear Interaction ◽  
Modulational Instability ◽  
Alfven Waves ◽  
Inertial Range ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Dynamical Equations ◽  
Turbulent Spectra ◽  
Kinetic Alfvén Waves

AbstractThe nonlinear interaction of kinetic Alfvén waves (KAWs) with other possible plasma modes is considered to be responsible for the observed solar wind turbulent spectrum. In the present paper, a new channel of interaction between a KAW and an obliquely propagating Alfvén wave (AW) has been proposed. The governing dynamical equations are derived and the nonlinear interaction between the two wave modes KAW and AW is studied. The growth rate of modulational instability has been calculated. The nonlinear evolution of KAW filamentation and turbulent spectra has also been discussed. In the inertial range, energy cascade follows nearly Kolmogorov scaling, and after inertial range it follows −2.5 scaling in dispersive range. The obtained results indicate that the proposed mechanism may be responsible for transferring the energy from smaller wavenumbers to larger wavenumbers in the solar wind plasmas. The relevance of the present study with recent Cluster spacecraft observations has also been pointed out.

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