Density cavities associated with inertial Alfvén waves in the auroral plasma

Sharma, R. P.; Singh, Harjit

doi:10.1029/2008ja013474

Cited by 20 publications

(15 citation statements)

References 57 publications

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“…Other ways of initiating plasma density variations have been elaborated in the auroral context. The ponderomotive force associated to the coupling of an Alfvén wave and an ion-acoustic wave could create deep density cavities (Sharma and Singh, 2009). On a larger scale, the growth of density variations is associated to the ionospheric feedback instability, which is a coupling of Alfvén waves with the ionosphere (Streltsov and Lotko, 2008).…”

Section: Discussionmentioning

confidence: 99%

Non-propagating electric and density structures formed through non-linear interaction of Alfvén waves

Mottez

2012

Ann. Geophys.

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Abstract. In the auroral zone of the Earth, the electron acceleration by Alfvén waves is sometimes seen as a precursor of the non-propagating acceleration structures. In order to investigate how Alfvén waves could generate non-propagating electric fields, a series of simulations of counter-propagating waves in a homogeneous medium is presented. The waves propagate along the ambient magnetic field direction. It is shown that non-propagating electric fields are generated at the locus of the Alfvén waves crossing. These electric fields have a component orientated along the direction of the ambient magnetic field, and they generate a significant perturbation of the plasma density. The non-linear interaction of down and up-going Alfvén waves might be a cause of plasma density fluctuations (with gradients along the magnetic field) on a scale comparable to those of the Alfvén wavelengths. The present paper is mainly focused on the creation process of the non-propagating parallel electric field.

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Section: Discussionmentioning

confidence: 99%

Non-propagating electric and density structures formed through non-linear interaction of Alfvén waves

Mottez

2012

Ann. Geophys.

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“…For comparison we found that the amplitude of the density dips of the order ∼ 0.07n 0 was presented by Kumar et al (2011) taking the inertial AW and magnetosonic wave in low beta plasma. Earlier, Sharma and Singh (2009) studied the inertial AW and ion-acoustic wave interaction numerically and reported the amplitude of the deepest density as ∼ 0.6n 0 for coronal plasmas. The variation in the density profile has also been studied by Kumar et al (2009) by considering kinetic AWs and ion acoustic waves in intermediate beta plasma.…”

Section: Discussionmentioning

confidence: 98%

Numerical study of density cavitations by inertial Alfvén waves

Kumar

Dwivedi

Sharma

et al. 2015

Astrophys Space Sci

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In this manuscript, we study the localization and density cavitations using inertial Alfvén wave (AW) and fast AW in the auroral ionosphere. We first develop a system of equations semi-analytically for both wave modes by using two-fluid model and then solve the model equations numerically using two-dimensional pseudo-spectral approach to analyze the localized structures and cavity formation at different instant of time. The ponderomotive force associated with the pump wave changes the background density and as the inertial AWs propagate through the modified density channel it gets localized. Therefore, the inertial AW splits up into filamentary/localized structures. A low frequency fast AW traveling through these complex structures created by inertial AW, is intensified having its own filamentary structures. The filamentary structures grow with time until the instability acquires steady state. We notice that the density cavities are also accompanied by the high amplitude magnetic fields. The amplitude of the strongest density cavity is estimated as ∼ 0.26n 0 (n 0 is unperturbed plasma num-B S. Kumar

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“…The above dynamical equation for IAW has numerically been studied by many authors (Shukla and Sharma, 2001;Singh and Sharma, 2006) and analytically (Sharma, Singh, and Malik, 2006;Singh and Sharma, 2007;Malik, Sharma, and Singh, 2007) for the case when ∂ x B y k 0x B y and ∂ z B y k 0z B y where k 0x (k 0z ) is the component of the wave vector perpendicular (parallel) toẑB 0 . But in the present manuscript we have considered ∂ x B y k 0x B y .…”

Section: Inertial Alfvén Wave Dynamicsmentioning

confidence: 98%

“…Many authors (Sharma, Singh, and Malik, 2006;Singh and Sharma, 2007;Malik, Sharma, and Singh, 2007) studied the saturated spectra of KAW/IAW and ion-acoustic turbulence by filamentation instability for the adiabatic and nonadiabatic case. They found that the spectra approach the Kolmogorov k −5/3 scaling.…”

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confidence: 99%

Cavitation by Nonlinear Interaction Between Inertial Alfvén Waves and Magnetosonic Waves in Low Beta Plasmas

2011

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This paper presents the model equations governing the nonlinear interaction between dispersive Alfvén wave (DAW) and magnetosonic wave in the low-β plasmas (β m e /m i ; known as inertial Alfvén waves (IAWs); here β = 8πn 0 T /B 2 0 is thermal to magnetic pressure, n 0 is unperturbed plasma number density, T (= T e ≈ T i ) represents the plasma temperature, and m e (m i ) is the mass of electron (ion)). This nonlinear dynamical system may be considered as the modified Zakharov system of equations (MZSE). These model equations are solved numerically by using a pseudo-spectral method to study the nonlinear evolution of density cavities driven by IAW. We observed the nonlinear evolution of IAW magnetic field structures having chaotic behavior accompanied by density cavities associated with the magnetosonic wave. The relevance of these investigations to low-β plasmas in solar corona and auroral ionospheric plasmas has been pointed out. For the auroral ionosphere, we observed the density fluctuations of ∼ 0.07n 0 , consistent with the FAST observation reported by Chaston et al. (Phys. Scr. T84, 64, 2000). The heating of the solar corona observed by Yohkoh and SOHO may be produced by the coupling of IAW and magnetosonic wave via filamentation process as discussed here.

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Density cavities associated with inertial Alfvén waves in the auroral plasma

Cited by 20 publications

References 57 publications

Non-propagating electric and density structures formed through non-linear interaction of Alfvén waves

Non-propagating electric and density structures formed through non-linear interaction of Alfvén waves

Numerical study of density cavitations by inertial Alfvén waves

Cavitation by Nonlinear Interaction Between Inertial Alfvén Waves and Magnetosonic Waves in Low Beta Plasmas

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