Electron Positron Ion Plasma Research Articles

Freak waves and electrostatic wavepacket modulation in a quantum electron–positron–ion plasma

The occurrence of rogue waves (freak waves) associated with electrostatic wavepacket propagation in a quantum electron–positron–ion plasma is investigated from first principles. Electrons and positrons follow a Fermi–Dirac distribution, while the ions are subject to a quantum (Fermi) pressure. A fluid model is proposed and analyzed via a multiscale technique. The evolution of the wave envelope is shown to be described by a nonlinear Schrödinger equation (NLSE). Criteria for modulational instability are obtained in terms of the intrinsic plasma parameters. Analytical solutions of the NLSE in the form of envelope solitons (of the bright or dark type) and localized breathers are reviewed. The characteristics of exact solutions in the form of the Peregrine soliton, the Akhmediev breather and the Kuznetsov–Ma breather are proposed as candidate functions for rogue waves (freak waves) within the model. The characteristics of the latter and their dependence on relevant parameters (positron concentration and temperature) are investigated.

Semiclassical relativistic fluid theory for electrostatic envelope modes in dense electron–positron–ion plasmas: Modulational instability and rogue waves

AbstractA fluid model is used to describe the propagation of envelope structures in an ion plasma under the influence of the action of weakly relativistic electrons and positrons. A multiscale perturbative method is used to derive a nonlinear Schrödinger equation for the envelope amplitude. Criteria for modulational instability, which occurs for small values of the carrier wavenumber (long carrier wavelengths), are derived. The occurrence of rogue waves is briefly discussed.

Polarization effect on the Raman backscattering of an electromagnetic wave propagating through an electron–positron–ion magnetoplasma

The present study is devoted to the investigation of stimulated Raman backscattering of an intense, circularly polarized electromagnetic wave in magnetized electron–positron–ion plasma. The nonlinear dispersion relation as well as the growth rate of instability is achieved. The effects of external magnetic field, fraction of electron–positron pairs, pump frequency and also the kind of polarization on the growth rate is studied. It is shown that an admixture of e–p pairs to the ion–electron plasma modifies the behavior of plasma with respect to the external magnetic field.

Head-on collision of electron acoustic solitary waves in dense magnetized electron–positron–ion plasma

In this paper, we study the head-on collision between two electron acoustic solitary waves (EASWs) in magnetized quantum electron–positron–ion plasma. Using the extended Poincaré–Lighthill–Kuo perturbation method, we obtain the Korteweg–de Vries equations, the phase shifts and the trajectories after the head-on collision of the two EASWs. It is found that the phase shifts are significantly affected by the values of the quantum parameter H, the ion to electron number density ratio δ, the electron cyclotron to electron plasma frequency ratio α and the obliqueness θ (propagation angle).

Modulational instability of ion-acoustic waves in electron–positron–ion plasmas

The stability of modulation of ion-acoustic waves in a collisionless electron–positron–ion plasma with warm adiabatic ions is studied. Using the Krylov–Bogoliubov–Mitropolosky (KBM) perturbation technique a nonlinear Schrödinger equation governing the slow modulation of the wave amplitude is derived for the system. It is found that for given set of parameters having finite ion temperature ratio (T i /T e ) the waves are unstable for the values of k lying in the range k min<k<k max. On increasing the ion temperature ratio (T i /T e ), it is found that k min and k max, both decreases and product PQ increases. The range of unstable region shifts towards the small wave number k, as temperature ratio (T i /T e ) increases. The positron concentration and temperature ratio of positron to electron, change the unstable region slightly. As positron concentration increases both k min and k max for modulational instability increases and maximum value of the product PQ shifts towards the larger value of k.

Magnetosonic shock waves in dense astrophysical electron–positron–ion plasmas

Multifluid quantum magnetohydrodynamic model (QMHD) is used to investigate small but finite amplitude magnetosonic shock waves in dense) electron–positron–ion (e–p–i) plasmas. The Korteweg–de Vries–Burgers (KdVB) equation is derived by using reductive perturbation method. It is noticed that variations in the positron density modify the profile of magnetosonic shocks in dense e–p–i plasmas significantly. The numerical results are also presented by taking into account the dense plasma parameters from published literature of astrophysical conditions, in compact stars. • Magnetoacoustic shock wave are studied in the quantum electron–positron–ion plasmas. • Multifluid quantum magnetohydrodynamic (QMHD) model is employed. • Reductive perturbation method is used to derive Korteweg–de Vries–Burgers equation. • The relevance of the work to neutron stars/pulsars has been pointed out.

Arbitrary amplitude ion-acoustic solitons in two-electron temperature warm ion plasma

The large amplitude Ion-acoustic solitons in collisionless plasma consisting of warm adiabatic ions, isothermal positrons and two-temperature distribution of electrons are investigated. Using pseudo-potential approach, an energy integral equation for the system has been derived which encompasses complete nonlinearity for the plasma system. The existence region of the solitons is analyzed numerically. It is found that for selected set of plasma parameters, both rarefactive and compressive solitons exist in the electron-positron-ion (EPI) plasma. It is also found that due to finite positron concentration both subsonic and supersonic rarefactive soliton exist in EPI plasma. An increase in finite ion temperature ratio decreases the amplitude of the rarefactive solitons. In the case of small amplitude, it is found that there exist supersonic compressive as well as rarefactive solitons simultaneously. The amplitude of the solitons decreases with increase in ion temperature ratio (σ), however an increase in positron concentration (α) and temperature ratio of positron to electrons (γ) increases the amplitude of the solitons. Effect of various plasma parameters on the characteristics of the solitons are discussed in detail. The results of the investigation may be helpful to understand the nonlinear structures in auroral plasma, pulsars and magnetospheric astrophysical environment as well as laboratory plasmas.

Ion-acoustic double layers in electron–positron–ion plasmas with finite ion temperature

AbstractThe large-amplitude ion-acoustic double layers in a collisionless plasma consisting of isothermal positrons, warm adiabatic ions and two-temperature distribution of electrons are investigated. Using the pseudo-potential approach, an energy-integral equation for the system has been derived which encompasses complete nonlinearity for the plasma system. The existence region of the double layers is analyzed numerically. It is found that for a selected set of physical parameters, the rarefactive double layer exists in the electron–positron–ion plasma. It is found that the existence regime of the double layer is very sensitive to the plasma parameters, e.g. cold electron concentration (μ) and temperature ratio of two electron species (β). An increase in the finite ion temperature ratio increases the amplitude of the rarefactive double layer. To study small-amplitude double layers, we have expanded the Sagdeev potential. In the case of small amplitude, it is found that the amplitude of the double layer increases with increase in ion temperature ratio (σ) and cold electron concentration (μ). However increase in positron concentration (α) and temperature ratio of positrons to electrons (γ) decreases the amplitude of the double layer. The effect of various plasma parameters on the characteristics of the double layers is discussed in detail. The results of the investigation may be helpful to understanding basic plasma characteristics in space.

Nonlinear interaction of intense laser pulses and an inhomogeneous electron-positron-ion plasma

The nonlinear interaction of an ultraintense short laser beam and an inhomogeneous electron-positron-ion (EPI) plasma is investigated. It is found that the presence of positrons and inhomogeneity results in strong modulational and filamentational instabilities, which induce strong nonlinear interactions between the laser beam and the inhomogeneous EPI plasma. Light beam focusing, filamentation, trapping, and nonlinear interaction between the trapped light spots and the inhomogeneous plasma are observed. Interestingly, we find that the inhomogeneity of the plasma can not only boost a mechanism for light beam self-focusing and filamentation but also provide an effective way to localize and trap the beam in the region one wanted.

The interaction of two nonplanar solitary waves in electron-positron-ion plasmas: An application in active galactic nuclei

In the present research paper, the effect of bounded nonplanar (cylindrical and spherical) geometry on the interaction between two nonplanar electrostatic solitary waves (NESWs) in electron–positron–ion plasmas has been studied. The extended Poincaré–Lighthill–Kuo method is used to obtain nonplanar phase shifts after the interaction of the two NESWs. This study is a first attempt to investigate nonplanar phase shifts and trajectories for NESWs in a two-fluid plasma (a pair-plasma) consisting of electrons and positrons, as well as immobile background positive ions in nonplanar geometry. The change of phase shifts and trajectories for NESWs due to the effect of cylindrical geometry, spherical geometry, the physical processes (either isothermal or adiabatic), and the positions of two NESWs are discussed. The present investigation may be beneficial to understand the interaction between two NESWs that may occur in active galactic nuclei.

Acoustic nonlinear periodic (cnoidal) waves and solitons in pair-ion plasmas

Electrostatic acoustic nonlinear periodic (cnoidal) waves and solitons are investigated in unmagnetized pair-ion plasmas consisting of the same mass ion species with different temperatures. It is found that the temperature difference between negatively and positively charged ions appropriates the dispersion property to linear acoustic waves and this difference has a decisive role in nonlinear dynamics as well. Using a reductive perturbation method and appropriate boundary conditions the Korteweg–de Vries equation is derived. Both cnoidal wave and soliton solutions are discussed in detail. In the special case, it is revealed that the amplitude of a soliton may become larger than what is allowed by the nonlinear stationary wave theory, which is equal to the quantum tunneling by a particle through a potential barrier effect. The serious flaw in the results obtained for ion acoustic nonlinear periodic waves by Yadav et al (1995 Phys. Rev. E 52 3045) in two-electron temperature plasmas and Chawla and Misra (2010 Phys. Plasmas17 102315) in electron–positron–ion plasmas is also pointed out.

Large amplitude dust-acoustic solitary waves in electron-positron-ion plasma with dust grains

Propagation of large amplitude dust-acoustic (DA) solitary waves is investigated in electron–positron–ion plasmas in the presence of dust grains using Sagdeev potential method. It is shown that acceptable values of Mach number for propagation of the large amplitude DA solitary waves depend strongly on plasma parameters. It is also observed that the amplitude of DA solitary waves increases as both the Mach number M and dust charge Zd are increased. Furthermore, it is found that a dusty plasma with inertial dust fluid and Boltzmann distributed electrons, positrons, and ions admits only negative solitary potentials associated with nonlinear dust-acoustic waves. In addition, it is remarked that the formation of double layers is not possible in this plasma system.

Nonlinear Propagation of Ion-Acoustic Shock waves in Dissipative Electron–Positron–Ion Plasmas with Superthermal Electrons and Relativistic Ions

Nonlinear Propagation of Ion-Acoustic Shock waves in Dissipative Electron–Positron–Ion Plasmas with Superthermal Electrons and Relativistic Ions

Nonlinear low-frequency structures in an electron–positron–ion plasma

AbstractNonlinear ion cyclotron and ion-acoustic waves have been studied in an electron–positron–ion plasma. Using Boltzmann distributions for the electrons and positrons and fluid equations for the ions, a set of nonlinear equations in the rest frame of the propagating wave is derived and numerically solved for the electric field. A scan of parameter space reveals a range of solutions for the parallel electric field, from sinusoidal to sawtooth to highly spiky waveforms. The results are compared with satellite observations.

Modulation instability of an intense laser beam in an unmagnetized electron–positron–ion plasma

The modulation instability of an intense circularly polarized laser beam propagating in an unmagnetized, cold electron–positron–ion plasma is investigated. Adopting a generalized Karpman method, a three-dimensional nonlinear equation is shown to govern the laser field. Then the conditions for modulation instability and the temporal growth rate are obtained analytically. In order to compare with the usual electron–ion plasmas, the effect of positron concentration is considered. It is found that the increase in positron-to-electron density ratio shifts the instability region towards higher vertical wave numbers but does not cause displacement along the parallel wave number direction, and the growth rate increases as the positron-to-electron density ratio increases.

Beltrami fields in a hot electron–positron–ion plasma

AbstractA possibility of relaxation of relativistically hot electron and positron (e − p) plasma with a small fraction of hot or cold ions has been investigated analytically. It is observed that a strong interaction of plasma flow and field leads to a non-force-free relaxed magnetic field configuration governed by the triple curl Beltrami (TCB) equation. The triple curl Beltrami (TCB) field composed of three different Beltrami fields gives rise to three multiscale relaxed structures. The results may have the strong relevance to some astrophysical and laboratory plasmas.

New exact solitary wave solutions of the Zakharov–Kuznetsov equation in the electron–positron–ion plasmas

In this paper, the Zakharov–Kuznetsov equation which describes the propagation of the electrostatic excitations in the electron–positron–ion (e–p–i) plasmas are investigated. New exact solitary wave solutions are obtained using Hirota’s bilinear method and generalized three-wave type of ansatz approach. These new exact solutions will enrich previous results and help us further understand the physical structures and analyze the dynamics of the electrostatic solitons in the e–p–i plasmas. Parametric analysis is carried out in order to illustrate that the soliton amplitude, width and velocity are affected by phase velocity, ion-to-electron density ratio, rotation frequency and cyclotron frequency.

Nonlinear structure of ion-acoustic solitary waves in a relativistic degenerate electron–positron–ion plasma

AbstractArbitrary amplitude and small amplitude ion-acoustic solitary waves (IASWs) have been investigated in a relativistic, collisionless, unmagnetized, and degenerate dense electron–positron–ion plasma. The arbitrary amplitude IASWs have been studied by using the Sagdeev-type pseudo-potential approach. Along with approximate solution, the exact amplitude solitary structure has also been studied numerically. The electrons and positrons are assumed to follow the corresponding Fermi distribution function and the ions are described by the hydrodynamic equations. A new dispersion relation for the ion-acoustic wave has been derived for the relativistic Thomas–Fermi plasma. An energy balance-like equation involving the Sagdeev-type pseudo-potential has been investigated and it has been shown that the concentration of plasma particles has significant effect on the permitted Mach number range of IASWs. Also, it has been pointed out that the only compressional supersonic IASWs can propagate in the relativistic Thomas–Fermi plasma. The present work would be helpful to understand the excitation of the nonlinear ion-acoustic waves in a degenerate plasma, such as in superdense white dwarfs and in the cores of massive planets.

Nonlinear Propagation of Ion-Acoustic Shock Waves in Dissipative Electron–Positron–Ion Plasma with Trapped Electrons and Relativistic Ions

Ion acoustic shock waves are studied in dissipative three-component plasma. Relativistic ions, Maxwell–Boltzmann distributed positrons, nonisothermal electrons are considered in the plasma and we also consider the kinematic viscosity among the plasma constituents. The dynamics of the nonlinear wave are governed by a modified Korteweg–de Vries Burger equation that possesses dissipative Burger term. The trapping parameter (β), the ratio of the free electron temperature to the trapped electron temperature, is treated as a variable. The effects of the coefficient of the kinematic viscosity, parameter β and also relativistic factor on the solitary and shock waves are studied.

Quantum ion–acoustic shock waves in warm dissipative electron–positron–ion plasmas with relativistic ions

Propagation of nonlinear quantum ion–acoustic shock waves in dense quantum plasma, whose constituents are electrons, positrons, and positive ions, is investigated using a quantum hydrodynamical model. Moreover, it is assumed that ion velocity is weakly relativistic. Also, we consider the effects of kinematic viscosity among the plasma constituents. By using reductive perturbation method, the Korteweg – de Vries – Burger equation is derived. The effects of relativistic ions, ion temperature, and the quantum Bohm potential on the shock waves are reported in this paper.