Magnetized Electron-ion Plasma Research Articles

Reductive perturbation method in magnetized plasma and role of negative ions

An analysis of reductive perturbation method (RPM) is presented to show why the solitary structures of non-linear ion acoustic waves (IAWs) cannot be obtained in magnetized electron ion plasma by employing this technique. In RPM, the non-linear Korteweg–de Vries equation is derived using stretched co-ordinates in the reference frame of the wave phase speed, considering the dispersion to be a higher-order effect that balances the non-linearity to produce a solitary structure. The maximum amplitude |Φm| of the non-linear solitary wave turns out to be larger than one that contradicts the small amplitude approximation. In the presence of negative ions, the maximum amplitude satisfies the condition |Φm|<1. To elaborate these points, the results have been applied to an experimental plasma consisting of positive ions of xenon (Xe+) and negative ions of fluorene (F−) along with electrons. The amplitude and width of the solitary structures depend upon the ratio of the electron to positive ion density (ne0ni0). Since the non-linear coefficient turns out to be negative, rarefied (dip) solitons are formed in the magnetized Xe+−F−−e plasma.

Dynamically screened strongly quantized electron transport in binary neutron-star merger

We examine electron-transport coefficients in magnetized hot and dense electron-ion plasma relevant in binary neutron star merger simulation. We calculate electrical and thermal conductivities in low density, high temperature, highly magnetized plasma of binary neutron star mergers where quantum oscillatory behavior of electrons emerge. For pronounced thermodynamic effects, we consider zeroth Landau level population of electrons for the calculation of conductivity. We solve Boltzmann equation in presence of magnetic field to obtain the dissipative components of electrical and thermal conductivities. The dissipative coefficients are formulated considering frequency dependent dynamical screening in the quantized electron-ion scattering rate. Numerical estimations show that the effect of dynamical screening of photon propagator on electrical and thermal conductivities is pronounced. We observe that dynamical screening reduces the maxima of both the electrical and thermal conductivities by factors of thirty one and twenty respectively leading to a reduction in the corresponding time scales of these coefficients. The common scaling factor between electrical and thermal conductivity is also observed to follow cubic relationship with temperature violating Wiedemann–Franz law.

Qualitative analysis of nonlinear electrostatic excitations in magnetoplasma with pressure anisotropy

Abstract The nonlinear propagation of ion-acoustic (IA) electrostatic solitary waves (SWs) is investigated in a magnetized electron-ion plasma in the presence of pressure anisotropy. The energy integral equation is derived by employing the Sagdeev approach. The current approach only allows for positive potential nonlinear structures. The effect of relevant plasma parameters on the characteristics of SW structures is investigated. The current study may be significant in space and astrophysical plasma systems.

Large amplitude electrostatic solitary waves in anisotropic plasma

The propagation of nonlinear ion-acoustic solitary waves (IASWs) is investigated in a magnetized anisotropic electron ion plasma with Cairns distributed electrons. The ions are warm and exhibit pressure anisotropy due to the external magnetic field. The energy integral equation for the wave potential is derived via Sagdeev approach. The effect of various physical plasma parameters (nonthermality, ion pressure anisotropy) on the characteristics of IASWs is investigated in detail. The present investigation could be of interest to space and astrophysical plasma systems having ion pressure anisotropy, for instance, in the magnetosphere and near earth magnetosheath.

Multiperiodic and chaotic wave phenomena of collective ion dynamics under KP-type equation in a magnetised nonextensive plasma

Dynamical features of small-amplitude ion-acoustic waves are investigated under KP-type equation in a magnetized electron-ion plasma, where electrons follow q-nonextensive distribution. To carry out this investigation, a four dimensional conservative dynamical system is proposed from this plasma model. By changing values of travelling wave velocity, ratio between ion gyro frequency and ion plasma frequency and q-nonextensive parameter, the system produces different dynamical features, such as periodic, multi-periodic, quasiperiodic, and chaotic ion-acoustic wave phenomena. It is observed that ratio between ion gyro frequency and ion plasma frequency plays the key role in the existence of ion-acoustic chaotic wave phenomenon. Also, existence of higher order periodic trajectories is seen to indicate chaotic phenomenon.

Oblique ion-acoustic solitary waves in anisotropic plasma with Tsallis distribution

The nonlinear propagation of ion-acoustic (IA) solitary waves (SWs) is studied in a magnetized electron-ion (EI) plasma in the presence of pressure anisotropy with Tsallis distribution. The energy integral equation is derived by employing the Sagdeev approach. The present model supports only positive potential nonlinear structures. The effect of relevant plasma parameters on the characteristics of IA solitary structures is investigated. The present investigation could be useful in space and astrophysical plasma systems.

Ion-scale solitary waves in magnetoplasma with non-thermal electrons

The propagation of ion acoustic (IA) solitary waves (SWs) is investigated in a magnetized electron-ion (EI) plasma with Cairns-Tsallis distributed electrons. A Zakharov-Kuznetsov (ZK) type equation is derived for the electrostatic potential via a reductive perturbation method (RPM). It is found that increasing values of non-extensive parameter q leads to reduction (enhancement) in amplitude of compressive (rarefactive) solitary structures. The amplitude of compressive (rarefactive) solitary wave (SW) decreases (increases) with increasing values of non-thermality parameter α. Furthermore, it is found that magnetic field strength Ω only affects the width of solitary structures.

Effect of relativistically degenerate electrons on linear and nonlinear structures in ion temperature gradient driven pure drift mode

Low frequency, electrostatic, pure drift mode is investigated in dense magnetized electron-ion plasma in the presence of relativistically degenerate electrons using quantum magnetohydrodynamic model (QMHD). Ions are considered as warm classical particles. Inhomogeneities in background ion density, ion temperature and external magnetic field are taken into account. In the linear regime, dispersion relation is obtained and plotted for both non-relativistic and ultra-relativistic regimes. Parametric study shows that for both non-relativistic and ultra-relativistic cases, growth rate of the wave increases by increasing, , which is the ratio of background ion temperature to density. In the nonlinear case, solitary solutions are obtained by using the functional variable method. Graphical illustrations are used to show the effect of relativistically degenerate electrons and other parameters like electron and ion number densities, magnetic field and ion temperature on nonlinear structures in both non relativistic and relativistic regimes. This work may be helpful to understand low frequency phenomena in dense inhomogeneous plasmas like neutron stars, white dwarfs and next generation lasers.

Investigation of supernonlinear and nonlinear ion-acoustic waves in a magnetized electron-ion plasma with generalized (r, q) distributed electrons

Bifurcations of nonlinear and supernonlinear ion-acoustic waves (IAWs) are studied in an electron-ion plasmas with generalized (r, q)-distributed electrons. The IAWs are examined under the Zakharov–Kuznetsov (ZK) and modified ZK equations using the reductive perturbation technique. Transforming both the ZK and mZK equations into their corresponding dynamical systems, all possible phase spaces and potential energy functions are analyzed. The nonlinear periodic and solitary wave solutions are obtained under the ZK and mZK equations. A newly discovered supernonlinear wave, in particular, supernonlinear periodic wave under the modified ZK equation in electron-ion magnetized plasma with (r, q)-distributed electrons is reported for the first time in the literature. Nonlinear and supernonlinear wave solutions are shown under the influence of physical parameters. The proposed study contributes to new wave motions in slow solar wind streams and astrophysical plasmas.

Surface waves on the inhomogeneous interface between radiative electron–ion plasma and vacuum

The impact of temperature inhomogeneity, surface charge and surface mass densities on the stability analysis of charged surface waves at the interface between dense, incompressible, radiative, self-gravitating magnetized electron–ion plasma and vacuum is investigated. For such an incompressible plasma system, the temperature inhomogeneity is governed by an energy balance equation. Adopting the one-fluid magnetohydrodynamic (MHD) approximation, a general dispersion relation is obtained for capillary surface waves, which takes into account gravitational, radiative and magnetic field effects. The dispersion relation is analysed to obtain the conditions under which the plasma–vacuum interface may become unstable. In the absence of electromagnetic (EM) pressure, astrophysical objects undergo gravitational collapse through Jeans surface oscillations in contrast to the usual central contraction of massive objects due to enhanced gravity. EM radiation does not affect the dispersion relation much, but actually tends to stabilize the Jeans surface instability. In certain particular cases, pure gravitational radiation may propagate on the plasma vacuum interface. The growth rate of radiative dissipative instability is obtained in terms of the wavevector. Our theoretical model of the Jeans surface instability is applicable in astrophysical environments and also in laboratory plasmas.

The characteristics of daughter waves emerging from colliding solitary waves in astrophysical plasma media

ABSTRACT The aim is to state the properties of ion acoustic solitary waves in course of collision and extract characteristics of the daughter wave in a magnetized electron–ion plasma. The magnetized plasma medium that is a constituent of white dwarfs and astrophysical plasmas that possesses relativistically degenerate electrons and thermal ions in the presence of a constant background magnetic field. The model is based on the extended Poincaré–Lighthill–Kuo (ePLK) method where a set of Korteweg–de Vries equations is obtained to show the phase shifts of colliding waves together with the amplitude and width of the born daughter solitary waves. The numerical results and presented figures regarding the amplitude and width of solitons provide a description of the influence of plasma parameters on soliton interactions, namely ion to electron temperature ratio (σi), ion cyclotron frequency (ωci), and angle between magnetic field and collision line (θ) together with their interplay in shaping the character of solitary waves. It is concluded that only rarefactive electrostatic non-linear waves are able to propagate in such plasma media. The daughter wave amplitude possesses a scaling behaviour regarding the impact angle. Interplay of the parameters on the phase shifts is presented. Ratio of amplitude and width of the daughter wave is directly proportional to the background field, the impact angle controls its maximum. It is observed that the magnetic field elevates ratio of the solitary wave amplitude to width leading it to a shorter life and hence interaction range with neighbouring sites.

Supernonlinear wave and multistability in magneto-rotating plasma with (r, q) distributed electrons

Supernonlinear ion-acoustic waves (IAWs) and their multistability are studied under the Zakharov-Kuznetsov (ZK) and modified ZK (mZK) equations in a rotating magnetized electron-ion plasma that consists of generalized (r, q)-distributed electrons. Bifurcation of IAW is presented through phase plane analysis and existence of IAW solutions is also shown through graphs of potential energy function. Supernonlinear wave exists for system corresponding to mZK equation with nonlinear periodic and solitary wave solutions. Effects of strength (q) and flatness (r) of the (r, q)-distribution on IAW solutions are shown along with other parameters, such as speed of the wave (V) and direction cosine (n). Furthermore, introducing an extraneous periodic perturbation, multistability property of the perturbed dynamical system is examined, and it is displayed using phase space and time series plots. Features of coexisting trajectories are examined for different values of spectral indices (r, q). Existence of two different types of chaos are supported through Lyapunov exponent graphs. Here, acceptable parametric values of spectral indices (r, q) are considered from data values of slow solar wind streams. Hence, supernonlinear periodic IAW and multistability property under the modified ZK equation are reported for the first time in rotating electron-ion magnetized plasma with (r, q)-distributed electrons. This study is applicable to understand supernonlinear wave features and multistability property of ion-acoustic wave motions featured in slow solar wind streams.

Mildly relativistic magnetized shocks in electron–ion plasmas – I. Electromagnetic shock structure

ABSTRACT Mildly relativistic shocks in magnetized electron–ion plasmas are investigated with 2D kinetic particle-in-cell simulations of unprecedentedly high resolution and large scale for conditions that may be found at internal shocks in blazar cores. Ion-scale effects cause corrugations along the shock surface whose properties somewhat depend on the configuration of the mean perpendicular magnetic field, that is either in or out of the simulation plane. We show that the synchrotron maser instability persists to operate in mildly relativistic shocks in agreement with theoretical predictions and produces coherent emission of upstream-propagating electromagnetic waves. Shock front ripples are excited in both mean-field configurations and they engender effective wave amplification. The interaction of these waves with upstream plasma generates electrostatic wakefields.

Phase plane analysis of small amplitude electron-acoustic supernonlinear and nonlinear waves in magnetized plasmas

Phase plane analysis of small amplitude electron-acoustic supernonlinear and nonlinear waves in a magnetized nonextensive electron-ion plasma is examined. These electron-acoustic waves (EAWs) are studied based on the Korteweg–de Vries (KdV) and modified Korteweg–de Vries (mKdV) equations. The dynamical systems for both the KdV and mKdV equations are formed using the propagating wave transfiguration. Phase plane analyses of EAWs corresponding to the KdV and mKdV equations are shown. Analytical solution corresponding to the electron-acoustic solitary wave for the KdV equation is derived. Analytical forms of kink, anti-kink and periodic wave solutions in ranges −1 < q < 0 and 0 < q < 1 are obtained for the mKdV equation. Superperiodic EAWs under the mKdV equation in the range q > 1 are shown numerically. Existence of small amplitude superperiodic EAWs under the mKdV equation is shown for the first time in a magnetized nonextensive electron-ion plasma using the concept of planar dynamical systems. Effects of system parameters on different traveling wave solutions of EAWs are displayed. Outcome of the study can be implemented to understand nonlinear and supernonlinear EAWs in space and atmosphere, such as, auroral zones and magnetosphere.

Nonlinear periodic coupled Alfvén and ion-acoustic wave structures in plasmas

The nonlinear propagation of coupled Alfvén and ion-acoustic waves is investigated in homogeneous, magnetized and collisionless electron-ion plasma. The ion parallel motion is included in the model so that ion-acoustic wave couples with Alfvén wave in plasmas. In linear limit, the dispersion relation of coupled Alfvén and ion-acoustic waves is derived and its dispersion effects are investigated analytically as well as numerically using laboratory plasma parameters, given in the literature. Using reductive perturbation method, the Korteweg–de Vries (KdV) equation is derived for nonlinear coupled Alfvén and ion-acoustic waves in plasmas by applying appropriate periodic boundary conditions. The cnoidal wave solution of coupled Alfvén and ion-acoustic waves in terms of Jacobian elliptic function (cn) is obtained and its soliton solution is also investigated. The numerical plots of cnoidal wave and soliton structures with variations of plasma β (defined as the ratio of kinetic pressure to magnetic pressure) and obliqueness of the wave propagation with respect to external magnetic field are presented for illustration. It is found that low amplitude compressive structures of nonlinear coupled Alfvén and ion-acoustic waves exist in a magnetized plasma, which moves with sub-Alfvénic wave speed.

Pair-beam propagation in a magnetized plasma for modeling the polarized radiation emission from gamma-ray bursts in laboratory astrophysics experiments.

The propagation of a relativistic electron-positron beam in a magnetized electron-ion plasma is studied, focusing on the polarization of the radiation generated in this case. Special emphasis is laid on investigating the polarization of the generated radiation for a range of beam-plasma parameters, transverse and longitudinal beam sizes, and the external magnetic fields. Our results not only help in understanding the high degrees of circular polarization observed in gamma-ray bursts, but they also help in distinguishing the different modes associated with the filamentation dynamics of the pair beam in laboratory astrophysics experiments.

Ion-scale Cnoidal Waves in a Magnetized Anisotropic Superthermal Plasma

The ion acoustic cnoidal waves (IACWs) are investigated in a magnetized anisotropic electron ion plasma with superthermal electron distribution. The ions are warm and manifest pressure anisotropy. ...

Interaction of counterstreaming rotating electron-positron beams with inhomogeneous electron-ion plasma

The interaction occurring between two counterstreaming rotating electron-positron beams and an inhomogeneous magnetized electron-ion plasma is studied with the focus of research on either positrons or electrons propagating in the direction of the magnetic field. Using the Vlasov theory along with geometrical optics, the linear eikonal equation corresponds to the gradient drift wave which is extracted in the background plasma, taking into account the beam contribution. The results reveal that the gradient drift instability is experienced where the gradients of density and temperature of electrons stand in the opposite directions, and in addition, the gradients act as destabilization effects. Regarding the beam contribution, when the electron beams propagate in the direction of the magnetic field, the parallel and perpendicular components of velocity and the Langmuir frequency of the rotating beams can induce stabilization effects on the unstable inhomogeneous configuration. However, as a considerable achievement, the mentioned stabilization effects vanish for the perpendicular velocity component lower than a certain threshold value. In addition, the destabilization effects of the characteristic parameters of the counterstreaming beams are observed as well, when the positron beams propagate in the direction of the magnetic field.

Phase mixing of lower hybrid modes in cold plasmas

In a fluid approach, nonlinear evolution of electrostatic lower hybrid modes is studied in a cold magnetized electron-ion plasma. The background magnetic field is assumed to be constant. In the frequency range of interest Ωci ≪ ω ≪ Ωce, the massive ions are treated as unmagnetized, and the electron inertia in the x-component of the momentum equation is neglected. The quasineutral plasma approximation is also relaxed. The dispersion relation for such low frequency modes reads as ω2=ωpi2/(1+ωpe2/Ωce2). Spatiotemporal evolution of such modes is analyzed by employing a simple perturbation technique. Our results show that an initially excited lower hybrid mode gradually loses its coherent nature due to phase mixing and eventually breaks even at an arbitrarily low amplitude. An estimate of the phase mixing time is also given, and it is found to increase as the strength of the magnetic field is enhanced. These results will be of relevance to space plasma situations and laboratory experiments.

Polarized Light from the Transportation of a Matter-Antimatter Beam in a Plasma.

A relativistic electron-positron beam propagating through a magnetized electron-ion plasma is shown to generate both circularly and linearly polarized synchrotron radiations, which is intrinsically linked with asymmetric energy dissipation of the pair beam during the filamentation instability dynamics in the background plasma. The ratio of both polarizations |⟨P_{circ}⟩/⟨P_{lin}⟩|∼0.15, occurring for a wide range of beam-plasma parameters, can help in understanding the recent observation of circularly polarized radiation from gamma-ray bursts.