scholarly journals The role of nonlinear Landau damping and the bounced motion of protons in the formation of dissipative structures in the solar wind plasma

1999 ◽  
Vol 6 (3/4) ◽  
pp. 161-167 ◽  
Author(s):  
M. Prakash ◽  
P. H. Diamond
Keyword(s):  
Solar Wind ◽  
Geomagnetic Field ◽  
Large Amplitude ◽  
Solar Wind Plasma ◽  
Acoustic Mode ◽  
Alfven Waves ◽  
Landau Damping ◽  
Alfvén Waves ◽  
Ion Acoustic ◽  
Nonlinear Landau Damping

Abstract. The present work examines the effects arising from the nonlinear Landau damping and the bounced motion of protons (trapped in the mirror geometry of the geomagnetic field) in the formation of nonlinear Alfvénic structures. These structures are observed at distances 1-5AU in the solar wind plasma (with ß ~ 1). The dynamics of formation of these structures can be understood using kinetic nonlinear Schrodinger (KNLS) model. The structures emerge due to balance of nonlinear steepening (of large amplitude Alfvén waves) by the linear Landau damping of ion-acoustic modes in a finite ß solar wind plasma. The ion-acoustic mode is driven nonlinearly by the large amplitude Alfvén waves. At the large amplitudes of Alfvén wave, the effects due to nonlinear Landau damping become important. These nonlinear effects are incorporated into the KNLS model by modifying the heat flux dissipation coefficient parallel to the ambient magnetic field. The effects arising from the bounced motion (of mirroring protons) are studied using a one-dimensional Vlasov equation. The bounced motion of the protons can lead to growth of the ion-acoustic mode, propagating in the mirror geometry of the geomagnetic field. The significance of these studies in the formation of dissipative quasistationary structures observed in solar wind plasma is discussed.

scholarly journals A dynamical model of plasma turbulence in the solar wind

2015 ◽  
Vol 373 (2041) ◽  
pp. 20140145 ◽  
Author(s):  
G. G. Howes
Keyword(s):  
Solar Wind ◽  
Solar Wind Plasma ◽  
Plasma Turbulence ◽  
Alfven Waves ◽  
Dynamical Model ◽  
Alfvén Waves ◽  
Small Scale ◽  
Current Sheets ◽  
Turbulent Fluctuations ◽  
Physical Mechanisms

A dynamical approach, rather than the usual statistical approach, is taken to explore the physical mechanisms underlying the nonlinear transfer of energy, the damping of the turbulent fluctuations, and the development of coherent structures in kinetic plasma turbulence. It is argued that the linear and nonlinear dynamics of Alfvén waves are responsible, at a very fundamental level, for some of the key qualitative features of plasma turbulence that distinguish it from hydrodynamic turbulence, including the anisotropic cascade of energy and the development of current sheets at small scales. The first dynamical model of kinetic turbulence in the weakly collisional solar wind plasma that combines self-consistently the physics of Alfvén waves with the development of small-scale current sheets is presented and its physical implications are discussed. This model leads to a simplified perspective on the nature of turbulence in a weakly collisional plasma: the nonlinear interactions responsible for the turbulent cascade of energy and the formation of current sheets are essentially fluid in nature, while the collisionless damping of the turbulent fluctuations and the energy injection by kinetic instabilities are essentially kinetic in nature.

scholarly journals A study of phase-steepened Alfvén waves in a high-speed stream at 0.29 AU

2000 ◽  
Vol 18 (8) ◽  
pp. 845-851 ◽  
Author(s):  
P. Alexander
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
A Priori ◽  
Solar Wind Plasma ◽  
Alfven Waves ◽  
Mhd Waves ◽  
Alfvén Waves ◽  
Interplanetary Physics ◽  
Speed Solar Wind ◽  
High Speed Solar Wind

Abstract. This work performs a search of phase-steepened Alfvén waves under a priori ideal conditions: a high-speed solar wind stream observed in one of the closest approaches to the Sun by any spacecraft (Helios 2). Five potential candidates were initially found following procedures established in earlier work. The observed cases exhibited arc-like or elliptical polarizations, and the rotational discontinuities that formed the abrupt wave edges were found at either the leading or the trailing part. The consideration of some additional specific parameters (mainly related to the relative orientation between mean magnetic field, wave and discontinuity) has been suggested here for an ultimate and proper identification of this kind of phenomenon. After the inclusion of these calculations in our analysis, even fewer cases than the five originals remain. It is suggested that optimum conditions for the detection rather than just for the existence of these events have to be reconsidered.Key words: Interplanetary physics (discontinuities; MHD waves and turbulence; solar wind plasma)

Similarity solutions for nonlinear Landau damping of Alfvén waves

1982 ◽  
Vol 28 (2) ◽  
pp. 317-323 ◽  
Author(s):  
J. F. McKenzie
Keyword(s):  
Power Spectrum ◽  
Basic Feature ◽  
Similarity Solutions ◽  
Alfven Waves ◽  
Landau Damping ◽  
Alfvén Waves ◽  
Wave Spectra ◽  
Initial Strength ◽  
Long Wavelength ◽  
Nonlinear Landau Damping

In this paper we develop similarity solutions for the problem of nonlinear Landau damping of Alfvén waves. These solutions which are applicable to power-law wave spectra illustrate not only the basic feature of the damping process, namely that short-wavelength waves decay more rapidly than long-wavelength waves, but also how the damping depends on the initial strength of the power spectrum and its distribution in wavenumber.

scholarly journals Evolution of Large-amplitude Alfvén Waves and Generation of Switchbacks in the Expanding Solar Wind

2021 ◽  
Vol 918 (2) ◽  
pp. 62
Author(s):  
Alfred Mallet ◽  
Jonathan Squire ◽  
Benjamin D. G. Chandran ◽  
Trevor Bowen ◽  
Stuart D. Bale
Keyword(s):  
Solar Wind ◽  
Large Amplitude ◽  
Alfven Waves ◽  
Alfvén Waves

A guiding centre Vlasov equation and its application to Alfvén waves

1969 ◽  
Vol 3 (3) ◽  
pp. 331-351 ◽  
Author(s):  
Jules A. Fejer ◽  
Joseph R. Kan
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Collisionless Plasma ◽  
Alfven Waves ◽  
Landau Damping ◽  
Alfvén Waves ◽  
Dielectric Tensor ◽  
Equilibrium Plasma ◽  
Warm Plasma ◽  
The Magnetic Field

Guiding centre approximations are used to derive the dielectric tensor of a collisionless plasma. This approximate dielectric tensor is used to obtain the dispersion relation of Alfvén waves in a warm plasma. In a ‘low/ β’ equilibrium plasma Alfvén waves are shown to suffer considerable Landau damping if the propagation vector is almost perpendicular to the magnetic field. In a non- equilibrium plasma Alfvén waves can be generated by ‘negative Landau damping’ even if β is low. For sufficiently high β the well-known ‘garden hose’ instability can occur and is then probably dominant. The importance of these two instabilities in the magnetosphere and in the solar wind is discussed.

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