Small amplitude Kinetic Alfven waves in a superthermal electron–positron–ion plasma

Adnan, Muhammad; Mahmood, S.; Qamar, Anisa; Tribeche, Mouloud

doi:10.1016/j.asr.2016.07.009

Cited by 16 publications

(10 citation statements)

References 49 publications

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“…Thus, the degenerate e-p-i plasma model under consideration supports only sub-Alfvénic compressive (Y > 0, m since < < u A 0 and 0 0 ) solitons which are associated with positive potential. The existence of compressive solitary KAWs at sub-Alfvenic speed in our degenerate e-p-i plasma system agrees to that reported in [12,15] but is different from [14] which shows the existence of both sub-and super-Alfvénic compressive solitons in nondegenerate e-p-i plasma. In what follows, we analyze our results numerically for plasma parameters relevant to dense astrophysical objects.…”

Section: Soliton Solution and Discussionsupporting

confidence: 89%

“…Thus, the degenerate e-p-i plasma model under consideration supports only sub-Alfvénic compressive (Y > 0, solitons which are associated with positive potential. The existence of compressive solitary KAWs at sub-Alfvenic speed in our degenerate e-p-i plasma system agrees to that reported in[12,15] but is different from[14] which shows the existence of both sub-and super-Alfvénic compressive solitons in nondegenerate e-p-i plasma.In what follows, we analyze our results numerically for plasma parameters relevant to dense astrophysical objects.Infigure 1,we have plotted the potential profiles of solitary KAWs depicting the effects of plasma b (a) and obliqueness parameter ( ) l z (b) for a set of other plasma parameters, as indicated in each panel. It can be readily seen from figure 1(a) that an increase of plasma b increases the width of the solitary KAWs without changing their amplitudes.…”

supporting

confidence: 90%

“…During the last few decades, a great deal of work has been done on the linear and nonlinear behavior of unmagnetized as well as magnetized e-p-i plasmas in order to understand the basic properties of waves excited there and to explain the different aspects of astrophysical environments where such plasmas exist. Among these works, investigations of nonlinear structures of kinetic Alfvén waves (KAWs) in e-p-i plasmas have also attracted much attention [9][10][11][12][13][14][15]. KAWs are dispersive Alfvén waves and can be excited in plasmas for Q=β=1 (β is the particle to magnetic pressure ratio; Q is the electron-to-ion mass ratio) when shear Alfvén waves, modified by perpendicular wave length effects, propagate obliquely in the direction of an ambient magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Solitary kinetic Alfvén waves in a dense electron–positron–ion plasma with degenerate electrons and positrons

Ahmed¹,

Sah²

2017

Plasma Sci. Technol.

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Through the use of a reductive perturbation technique, solitary kinetic Alfvén waves (KAWs) are investigated in a low but finite b (particle-to-magnetic pressure ratio) dense electron-positron-ion plasma where electrons and positrons are degenerate. The degenerate plasma model considered here permits the existence of sub-Alfvénic compressive solitary KAWs. The influence of r (equilibrium positron-to-ion density ratio), s F (electron-to-positron Fermi temperature ratio), b and obliqueness parameter l z on various characteristics of solitary KAWs are examined through numerical plots. We have shown that there exists a critical value of l z at which a soliton width attains its maximum value which decreases with an increase in r and s. F It is also found that solitons with a higher energy propagate more obliquely in the direction of an ambient magnetic field. The results of the present investigation may be useful for understanding low frequency nonlinear electromagnetic wave propagation in magnetized electron-positron-ion plasmas in dense stars. Specifically, the relevance of our investigation to a pulsar magnetosphere is emphasized.

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Section: Soliton Solution and Discussionsupporting

confidence: 89%

supporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Solitary kinetic Alfvén waves in a dense electron–positron–ion plasma with degenerate electrons and positrons

Ahmed¹,

Sah²

2017

Plasma Sci. Technol.

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“…It is worth mentioning that modification of Alfvén waves has been investigated both analytically and numerically in the literature [92–94]. Since in our arguments the velocity/amplitude of the Alfvén velocity is modified depending on the sign of the parameter ξ , one may argue that such a theory may explain structural changes of small amplitude kinetic Alfvén solitary waves [95] or those occurring in a low beta plasma characterized by superthermal electrons and positrons [96] in a completely different state-of-the-art. In the next section, we will explore the implications of NS-MHD in solar physics and in particular sunspots.…”

Section: Non-standard Magnetohydrodynamics Equations: a Quick Review ...mentioning

confidence: 99%

Non-standard magnetohydrodynamics equations and their implications in sunspots

El-Nabulsi¹

2020

Proc. R. Soc. A.

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In this work, we study the physics of plasma waves and magnetohydrodynamic (MHD) equilibrium of sunspots based on the concept of non-standard Lagrangians which play an important role in several branches of science. We derived the modified fluid equations from the Maxwell–Vlasov equation using the moment conventional procedure. Several new interaction terms between physical quantities arise in the non-standard MHD (NS-MHD) equations that give rise to additional features in plasma MHD. A number of fundamental problems in plasma physics are discussed including the non-relativistic dynamics of inviscid fluid subject to the gravitational field, linear waves in plasma MHD and MHD equilibrium of sunspots. For the case of magnetoacoustic wave, it was observed that the NS-MHD equations modify the dispersion relation and its corresponding velocity depends on the sign (positive or negative) of the free parameters introduced in the theory. The non-standard Alfvén velocity is greater than the standard Alfvén velocity for the negative sign and smaller for the positive sign. Besides, in the MHD equilibrium of sunspots, non-standard MHD extends the conventional problem by adding several constraints that lead to an emergence of very low temperature inside the magnetic flux tube comparable to what is observed in low-temperature superconductors. Additional consequences are discussed accordingly.

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“…Non‐linear magnetohydrodynamic (MHD) waves have received much attention because they are used as a mechanism for understanding solar corona heating, plasma dynamics in thermonuclear devices, and particle acceleration . The acoustic, Alfvén, and magnetoacoustic waves are the three fundamental modes of MHD in plasmas . A magnetoacoustic wave propagates in the direction perpendicular to the ambient magnetic field .…”

Section: Introductionmentioning

confidence: 99%

Interaction of magnetoacoustic solitons in plasmas with dispersion effects through electron inertia

Shahida

Mahmood

Qamar

et al. 2018

Contributions to Plasma Physics

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The head-on collision between two magnetoacoustic solitons is investigated in a magnetized plasma containing inertial cold ions and warm electrons. A two-fluid magnetohydrodynamic (MHD) model is used to study the magnetoacoustic solitons interaction in plasmas. The magnetoacoustic wave dispersion effects appearing through electron inertial length (skin depth) are also included in the model. By using the extended Poincaré-Lighthill-Kuo (PLK) method, the Korteweg-de Vries (KdV) equations are derived for the low amplitude left and right moving magnetoacoustic solitons, their trajectories, and corresponding phase shifts after their elastic collisions are obtained analytically and examined numerically as well. It is found that only positive polarity (compressive) soliton structures of magnetoacoustic waves are formed. The profiles of head-on collision and the time evolution of two compressive interacting magnetoacoustic solitons are also presented for illustration. The effect of plasma beta, which depends on plasma density, electron temperature, and magnetic field intensity, on the phase shift of the interacting magnetoacoustic solitons is also examined.

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Small amplitude Kinetic Alfven waves in a superthermal electron–positron–ion plasma

Cited by 16 publications

References 49 publications

Solitary kinetic Alfvén waves in a dense electron–positron–ion plasma with degenerate electrons and positrons

Solitary kinetic Alfvén waves in a dense electron–positron–ion plasma with degenerate electrons and positrons

Non-standard magnetohydrodynamics equations and their implications in sunspots

Interaction of magnetoacoustic solitons in plasmas with dispersion effects through electron inertia

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