Electron Acoustic Waves Research Articles

The electron acoustic waves in plasmas with two kappa-distributed electrons at the same temperatures and immobile ions

The linear electron acoustic waves propagating in plasmas with two kappa-distributed electrons and stationary ions are investigated. The temperatures of the two electrons are assumed to be same, but the kappa indices are not. It shows that if one kappa index is small enough and the other one is large enough, a weak damping regime of the electron acoustic waves exists. The dispersions and damping rates are numerically studied. The parameter spaces for the weakly damped electron acoustic waves are analyzed. Moreover, the electron acoustic waves in the present model are compared with those in other models, especially the plasmas with two-temperature electrons. At last, we perform Vlasov–Poisson simulations to verify the theory.

The Existence and Propagation of Electron Acoustic Shock Waves in Magnetized Plasma with Electron Beam

The Existence and Propagation of Electron Acoustic Shock Waves in Magnetized Plasma with Electron Beam

Electron Heat Flux Instabilities in the Inner Heliosphere: Radial Distribution and Implication on the Evolution of the Electron Velocity Distribution Function

Abstract This Letter investigates the electron heat flux instability using the radial models of the magnetic field and plasma parameters in the inner heliosphere. Our results show that both the electron acoustic wave and the oblique whistler wave are unstable in the regime with large relative drift speed (ΔV e ) between electron beam and core populations. Landau-resonant interactions of electron acoustic waves increase the electron parallel temperature that would lead to suppressing the electron acoustic instability and amplifying the growth of oblique whistler waves. Therefore, we propose that the electron heat flux can effectively drive oblique whistler waves in an anisotropic electron velocity distribution function. This study also finds that lower-hybrid waves and oblique Alfvén waves can be triggered in the solar atmosphere, and that the former instability is much stronger than the latter. Moreover, we clarify that the excitation of lower-hybrid waves mainly results from the transit-time interaction of beaming electrons with resonant velocities v ∥ ∼ ω/k ∥, where ω and k ∥ are the wave frequency and parallel wavenumber, respectively. In addition, this study shows that the instability of quasi-parallel whistler waves can dominate the regime with medium ΔV e at the heliocentric distance nearly larger than 10 times of the solar radius.

Characteristics of solitary waves, breather waves and hybrid waves to a new (3 + 1)-dimensional nonlinear evolution equation in a quantum magnetoplasma

By considering the nonlinear propagations of electron acoustic waves in quantum magnetoplasmas, we successfully derive a new ()-dimensional nonlinear evolution equation (NLEE) via the standard reductive perturbation theory. Through introducing a suitable transformation, the Hirota's bilinear equation of the ()-dimensional NLEE is first found analytically. Some interesting mathematical analytical results are further investigated, including some dynamics of solitary waves, breather waves, and hybrid waves. Based on the resulting bilinear form, an effective method is presented to find its N-solitary wave solutions. Moreover, by taking particular complex conjugate conditions, we further obtain its N-th–order breather wave solutions and general hybrid wave solutions which have not been reported yet. Finally, some significant characteristics of these nonlinear waves are illustrated to better understand their dynamical behavior. For these analytic solutions, the influences of each parameter on the dynamics of solitary waves, breather waves, and hybrid waves are discussed, and the method of how to control such nonlinear waves is also suggested.

Theoretical analysis of electron acoustic shock waves in magnetized superthermal plasma with electron beam

AbstractWe have analysed the small‐amplitude non‐linear electron acoustic shock waves by taking into account the effects of electron beam in magnetized plasma. Satellite observations in different regions of the Earth's magnetosphere have shown that the electrostatic solitary waves are generally associated with electron or/and ion beams. The nonlinear Korteweg‐de‐Vries Burgers (KdVB) equation has been derived by considering the basic fluid equations and dissipation effects. The nonlinear coefficient of KdVB equation comes out to be negative. Only dip‐shaped potential structures are reported here. For the parameters discussed in this paper, we did not find positive polarity shocks. This could be due to the restrictions on the plasma parameters since we are using the fixed densities of the cold, hot, and beam electrons as observed by the Viking satellite in the auroral region. In this paper, the importance of the cold electron to hot electron temperature in conjunction with the beam speed is pointed out. Increase in beam density, kinematic viscosity, and magnetic field results in increase in the amplitude while the increase in hot electron concentration and superthermality leads to decrease in potential. The numerical analysis is presented for the parameters corresponding to the observation of burst b event by Viking satellite in the dayside auroral zone of the earth's magnetosphere.

KBM approach to electron acoustic envelope soliton in viscous astrophysical plasma

Modulation instability (MI) of envelope soliton is studied in an unmagnetized viscous plasma. Using Krylov-Bogoliubov Mitropolsky (KBM) method, the nonlinear Schrödinger equation (NLSE) is obtained, and the growth rate of modulationally unstable electron acoustic wave in such plasma is discussed. The solution of the electron-acoustic envelope-solitons is obtained from the Nonlinear Schrödinger equation. The hypothetical outcomes have been examined mathematically for various parameters of plasma, and the outcomes are introduced graphically. This theoretical investigation can be experienced experimentally with certain modification of the experiment had been performed by Ikezawa and Nakamura []. Our outcomes might be material for the investigation of nonlinear wave measures in relativistic thick plasmas of astrophysical articles, to be specific, in dwarfs and neutron stars.

Non‐linear behaviour of electron acoustic wave dynamics in a magnetized plasma with non‐thermal hot electrons

AbstractNon‐linear dynamical behaviour of electron acoustic waves (EAWs) is studied in a magnetized non‐thermal plasma (containing inertial cold electrons, inertialess hot electrons following non‐thermal distribution function, and static ions) via a fluid dynamical approach. A linear dispersion relation is derived and the propagation of two possible modes and their evolution are studied through the different plasma configuration parameters, such as non‐thermality and external magnetic field strength. In a non‐linear perturbation regime, a reductive perturbation technique is employed to derive the non‐linear evolution equation and the analysis is executed for travelling plane waves in terms of a non‐linear dynamical system to enlighten the numerous aspects of the phase space dynamics. The results of numerical simulation predict the existence of a wide class of non‐linear structures, namely solitonic, periodic, quasiperiodic, and chaotic depending upon different controlling plasma parameters. Also, Poincaré return map analysis confirms these non‐linear structures of the EAWs.

Analysis of electron acoustic waves interaction in the presence of homogeneous unmagnetized collision-free plasma

In this research, the transmission and interaction of nonlinear electron acoustic waves (EAWs) in such an unmagnetized, homogeneous, collision-free plasma composed of hot and cold electrons together with stationary ions throughout in the background have been analyzed. For the small-amplitude limit, the Korteweg–de Vries (KdV) equation for (EAWs) have been extracted. For electron acoustic solitary waves (EASWs), using the new extended direct algebraic approach, soliton solutions have also documented. The parametric analysis demonstrated that the hot to cold electron ratio and hot electron superthermal play a key role in changing the (EASWs) amplitude. The family of semi-bright solitons, dark singular solitons, Type 1 as well as 2 single solitons, trigonometric, intermingled hyperbolic and rational solitons was constructed and tested with the assistance of the innovative package software of numerical computations. The results show that the method is clear and efficient, produces analytical results in a generalized form, and these findings can also help resolve the difficulties and predicaments in the relevant disciplines of plasma physics and may be useful for studying the relationship between two (EASWs) in astrophysical and laboratory plasma. The solutions presented in this prototype are the latest in a literature review. For physical interpretation, some randomly selected solutions are shown graphically. Conclusions are held at the end.

Multimode excitation and modulational instability of beam plasma system with Tsallis-distributed electrons

In the present investigation, authors have studied the linear mode structure of electron-acoustic waves, their modulational instability and rogue wave profiles in four-component plasma system consisting of stationary ions, cold electron fluid, Tsallis-distributed hot electrons and an electron beam. By applying standard perturbation method to the fluid equations, the dispersion relation is obtained that depends on various parameters such as beam density, beam velocity, beam temperature and non-extensivity q. Based on the phase velocities, two electron-acoustic (EA) modes known as slow and fast, have been extracted as real modes for which a detailed analysis is presented. Further, the basic set of equations is reduced to nonlinear Schrodinger equation (NLSE), where the nonlinearity and dispersion coefficients compete and significantly affect the stability characteristics of EA waves. For both the modes, a comprehensive study of modulational instability and rogue wave profile has been carried out by taking into consideration the effect of non-extensivity and beam velocity. The obtained results have been compared with other research works. The present investigation may be relevant to the observation from Viking satellite in the day-side auroral zone.

Amplitude-modulated electron-acoustic waves with bipolar ions and kappa-distributed positrons and warm electrons

In this paper, we have meticulously studied the amplitude modulation of electron-acoustic waves and the formation and properties of envelope solitons in a five-component complex plasma containing statistically kappa-distributed warm and cold electrons, kappa-distributed positrons and Boltzmann-distributed positive and negative ions. The picture considered here is very similar to solar atmosphere and planetary environments. The parametric dependence of modulational instability on kappa index, positron and electron densities, ion and reciprocal of positron temperatures has been studied in detail and the findings obtained here will be beneficial for further astrophysical investigations.

Finite amplitude electron-acoustic waves in the electron diffusion region

The electron-acoustic solitons are studied with two temperature electrons (a hot trapped having vortex-like velocity distribution and a warm adiabatic fluid) and stationary ions. The theoretical model is based on the observations of a mixture of the hot, tenuous magnetospheric and warm, dense magnetosheath plasma particles associated with the asymmetric magnetic reconnection at the Earth’s magnetopause by Magnetospheric Multiscale (MMS). Using the reductive perturbation technique, the model supports the existence of nonlinear electron-acoustic structures derived from the mKdV-like equation. The electron-acoustic waves propagate at supersonic speeds above the electron sound speed. The results are applied to observations of electric field structures in the electron diffusion region (EDR).

Electron acoustic solitary waves in unmagnetized nonthermal plasmas

Electron acoustic (EA) solitary waves (SWs) are studied in an unmagnetized plasma consisting of hot electrons (following Cairns-Tsalli distribution), inertial cold electrons, and stationary ions. By employing a reductive perturbation technique (RPT), the nonlinear Korteweg–de Vries (KdV) equation is derived and its SW solution is analyzed. Here, the effects of plasma parameters such as the nonextensivity parameter (q), the nonthermality of electrons (α), and the cold-to-hot electron density ratio (β) are investigated.

Determination of maximum electric field amplitude sustained by electron acoustic solitary waves in an unmagnetized plasma with kappa-distributed electrons

This manuscript investigates the maximum electric field amplitude sustained by nonlinear electron acoustic waves, without losing their initial structure, and propagating in an unmagnetized homogeneous plasma comprising cold inertial electrons, hot kappa-distributed electrons, and stationary ions. Using nonlinear fluid Maxwell’s equations in one dimension, traveling wave solutions have been derived in the wave frame, and negative potential solitary structures have been observed. Furthermore, a pseudo-potential method has been employed to determine the maximum electric field amplitude as a function of the dimensionless Mach number (M), initial density ratio of hot to cold electron species (Rn=nh0nc0), and spectral index (κ) of the hot electron species velocity distribution function. We find that at this maximum electric amplitude, the density of the cold electron fluid becomes singular and thus can be called the wave breaking limit [J. M. Dawson, Phys. Rev. 113, 383 (1959)]. Density singularity is an artifact of the cold fluid plasma model and actually diminishes if one introduces a nonzero temperature to the cold inertial electrons. In that case, we find that the maximum electric field amplitude gets modified and follows the same scaling as the ratio of cold to hot electron species temperature (σ=TecTeh), as obtained by Coffey [Phys. Fluids 14, 1402 (1971)], with electron thermal velocity derived for the wave breaking limit of electron plasma waves in a warm plasma.

Nonlinear coherent structures of electron acoustic waves in unmagnetized plasmas

The propagation dynamics of nonlinear electron acoustic waves (EAW) are explored analytically and numerically in collisionless unmagnetized plasmas. The dynamics of the nonlinear wave is shown to be governed by a Boussinesq equation. In the supersonic range, the wave becomes unstable in the short wave limit. In the nonlinear stage, this unstable mode reaches a maximum values and after that it damps. Different limiting cases of the general solutions are discussed. Analytical and computational results predict that the nonlinear EAW possesses breather structures apart from the usual solitary wave solutions. The results are discussed in the context of astrophysical plasmas.

Mode Coupling From Kinetic Alfvén Waves to Electron Acoustic Waves in the Topside Ionosphere

AbstractThe propagation and energy transfer of kinetic Alfvén waves (KAWs) in the topside ionosphere are investigated based on a drift kinetic model. We examine the dependence of the generation of electron acoustic waves (EAWs) on the perpendicular wavelength and on the hot electron temperature. With decreasing perpendicular wavelength and increasing hot electron temperature, the coupling of KAWs to EAWs becomes increasingly important. The Landau damping of the EAWs is strong except in the transition region, where the nonlinear dissipation can be important. With increasing wave amplitude, the generated electron acoustic mode waves become unsustainable when the depletion of cold electron density is comparable to the initial background cold electron density. These findings indicate that electron acoustic mode waves play an important role at kinetic scales in the topside ionosphere.

Evolution of nonlinear stationary formations in a quantum plasma at finite temperature

Abstract In this paper we have studied the gradual evolution of stationary formations in electron acoustic waves at a finite temperature quantum plasma. We have made use of Quantum hydrodynamics model equations and obtained the KdV-Burgers equation. From here we showed how the amplitude modulated solitons evolve from double layer structures through shock fronts and ultimately converging into solitary structures. We have studied the various parametric influences on such stationary structure and also showed how the gradual variations of these parameter affect the transition from one form to another. The results thus obtained will help in the generation and structure of the structures in their respective domain. Much of the experiments on dense plasma will benefit from the parametric study. Further we have studied amplitude modulation followed by a detailed study on chaos.

Arbitrary amplitude electron-acoustic solitons and double layers with Cairns–Tsallis-distributed hot electrons

In the present research paper, propagation attributes of nonlinear electron-acoustic (EA) waves have been investigated in an unmagnetised plasma system consisting of cool fluid electrons and hot electrons observing the hybrid Cairns–Tsallis distribution. Sagdeev pseudopotential method has been used to explore the occurrence of large-amplitude solitons and double layers, focussing on how their characteristics depend upon different parameters. The analysis is further extended to examine the dynamics of large- and small-amplitude double layers. It is revealed that the present plasma system supports the existence of negative potential solitons and double layers in certain region of parameter space. The numerical results show that the Cairns–Tsallis-distributed hot electrons may affect the spatial profiles of EA waves and double layers. The present investigation may be relevant to the observation from Viking satellite in the dayside auroral zone.

Characteristics of supernonlinear and coexistence features for electron-acoustic waves in an adiabatic quantum plasma

Bifurcation of quantum electron-acoustic waves (QEAWs) is studied in an adiabatic quantum plasma with nonextensively distributed hot electrons. Using reductive perturbation technique, modified Kortweg de Vries (KdV) equation is derived with dual power nonlinearity for highly nonlinear QEAWs. Using Galilean transformation the modified KdV equation is reduced to a planar dynamical system with three equilibrium points. Applying phase plane analysis periodic wave solutions and supernonlinear periodic wave solutions for QEAWs are perceived. It is found that the amplitude of the nonlinear structures is indirectly proportional to the ratio of number densities ( $$\mu $$ ), the cold to hot electron temperature ratio ( $$\sigma $$ ) and the nonextensivity parameter (q), we have explained physically that confronts our results. In addition, coexistence of superperiodic and quasiperiodic phenomena, quasiperiodic and chaotic phenomena and chaotic, superperiodic and quasiperiodic phenomena for QEAWs are observed for appropriate initial values.

In search of hyperchaos in a high dimensional unmagnetized quantum plasma

Abstract The hyperchaos and multistability of electron acoustic waves in a quantum plasma model comprising of nondegenerate cold and degenerate hot electrons and stationary ions are investigated. A six-dimensional dynamical system is constructed from the fluid equations of the model considering traveling wave transformation. The stability analysis of the system is done by finding out the equilibria in the inertia frame. It is interesting to investigate that though the novel system is conservative, it can produce hyperchaos for a set of associated parameters. We have also reported the coexistence of many hyperchaotic attractors as the system is extremely sensitive to the initials. The signature of hyperchaos and coexisting hyperchaos in a conservative quantum plasma system has never been reported before.

The Electron Acoustic Wave and Its Role in Solar Flaring Loops Heating

Abstract From soft X-ray emission, the solar flare temperatures are from several MK to dozens of times MK, which are higher than the preflare coronal temperatures. A combination of several heating mechanisms may contribute to the heating problem in solar flare loops. In this paper, we propose an important mechanism of solar flaring loops heating, in which the excited electron acoustic wave (EAW) by flare-accelerated fast electron beams can lead to electron heating via collisionless Landau damping effect produced by wave–particle resonant interaction. Taking account of the return-current effect of fast electron beams, by use of numerical and analytic solutions, the plasma wave instability driven by fast electron beams is investigated in typical solar flare loop plasma parameters. The results show that the EAW is the strongest unstable wave mode rather than other wave modes. The dissipation of EAW via collisionless Landau damping and its application to solar flaring loops heating are discussed in detail.