Magnetized Electron-positron Plasma Research Articles

Several nonlinear waves in spin quantum electron-positron plasmas

By using the reductive perturbation method, we obtained a nonlinear Schrödinger equation considering spin properties for a magnetized electron-positron plasmas. Several nonlinear wave were studied. The results indicate that various types of nonlinear waves exist in a magnetized electron-positron plasmas and they are spatially localized in both parallel and vertical directions to the external magnetized field direction. Additionally, the dependence of the wave amplitudes, wave width in both direction, group velocity of the envelop wave and the phase velocity of the background waves for these kinds of the nonlinear waves on the system parameters are all given in the present paper.

A weakly nonlinear Ion-acoustic waves in magnetized electron-positron plasma: a fractional model

A weakly nonlinear Ion-acoustic waves in magnetized electron-positron plasma: a fractional model

Traveling Wave Solutions for Time-Fractional mKdV-ZK Equation of Weakly Nonlinear Ion-Acoustic Waves in Magnetized Electron–Positron Plasma

In this paper, we discuss the time-fractional mKdV-ZK equation, which is a kind of physical model, developed for plasma of hot and cool electrons and some fluid ions. Based on the properties of certain employed truncated M-fractional derivatives, we reduce the time-fractional mKdV-ZK equation to an integer-order ordinary differential equation utilizing an adequate traveling wave transformation. Further, we derive a dynamical system to present bifurcation of the equation equilibria and show existence of solitary and kink singular wave solutions for the time-fractional mKdV-ZK equation. Furthermore, we establish symmetric solitary, kink, and singular wave solutions for the governing model by using the ansatz method. Moreover, we depict desired results at different physical parameter values to provide physical interpolations for the aforementioned equation. Finally, we introduce applications of the governing model in detail.

INVESTIGATION OF THE ELABORATE DYNAMICS OF WEAKLY NONLINEAR FRACTIONAL ION-ACOUSTIC WAVES IN MAGNETIZED ELECTRON–POSITRON PLASMA

This study employs three advanced computational and numerical techniques to solve the nonlinear fractional modified Korteweg–de Vries–Zakharov–Kuznetsov (mKdV–ZK) equation in magnetized plasma. The reductive perturbation approach is utilized to investigate the dynamics of various components, namely isothermal species, immobile background species, and warm adiabatic fluid, in magnetized plasma. Emphasis is placed on unraveling the asymmetrical propagation characteristics of nonlinear electrostatic waves. The model’s solutions encompass diverse types of solitons, including ion-acoustic, dust acoustic, and electron acoustic solitons. Analytical solutions are obtained using a variety of mathematical functions, such as exponents, trigonometry, and hyperbolas. Two- and three-dimensional density graphs illustrate the practical behavior of a single soliton. The primary objective of employing numerical schemes is to assess the accuracy of the derived solutions, and the outcomes demonstrate the efficacy of the analytical method in solving nonlinear mathematical and physical problems. Several techniques are employed to validate the consistency between calculated and estimated results, ensuring the study’s accuracy and reliability. Overall, this investigation underscores the effectiveness of numerical and analytical techniques in tackling complex mathematical models, offering a promising avenue for future research in the field. The findings carry significant implications for comprehending nonlinear phenomena in magnetized plasma and contribute to advancing the field.

Solitons’ behavior of waves by the effect of linearity and velocity of the results of a model in magnetized plasma field

The nonlinear three-dimensional modified Korteweg-de Vries-Zakharov-Kuznetsov model plays the behavior of weakly nonlinear ion-acoustic waves in a magnetized electron-positron plasma, containing the same capacity of cool and hot components of each species. In this article, we have investigated the mathematical model namely, (3 + 1)-dimensional modified KdV-Zakharov-Kuznetsov equation through the new auxiliary equation method for locating the closed-form travelling and solitary wave solutions. We have constructed a well-built 3D wave profile that signifies the variations in the same solution for particular values of the associated parameters. The novel point of this article is that, the generic values of the velocity parameter (λ) of the obtained solutions represent in the wave profile which thoroughly explains the reasons for the change in the variation of solitons. Besides, the type of wave profile subject to different values ​​of all other parameters that are related to the linearity of the stated model is also discussed. We have obtained numerous new wave solutions that establish the effectiveness of the implemented method in solving evolution equation which is nonlinear in nature and has higher dimension (HNEEs).These discussions may be useful or helpful in further research on this model. Besides, the implemented method is reliable for exploring important nonlinear waves that improve a variety of dynamic models arising in nonlinear science, mathematical physics, and engineering fields.

Abundant stable and accurate solutions of the three-dimensional magnetized electron-positron plasma equations

This paper tries constructing analytical and numerical solutions of three-dimensional magnetized electron-positron plasma equations. In magnetized electron-positron plasma with equally hot and cool components of each species, these waves demonstrate weakly nonlinear ion-acoustic characteristics that make studying their dynamical behavior an essential target for its applications. A reduction perturbation method was previously employed to convert this model into the three-dimensional modified Korteweg–de Vries-Zakharov–Kuznetsov (3D KdV–ZK) equation. Operating two recent analytical techniques to the transformed equation gets abundant traveling wave solutions that are used to construct the requested conditions for applying a semi-analytical scheme. Furthermore, the stability property of obtained analytical solutions has been studied. The purposed analytical and semi-analytical method’s performance is investigated to show their power, effectiveness for applying to some nonlinear evolution equations.

Radiative Turbulent Flares in Magnetically Dominated Plasmas

Abstract We perform 2D and 3D kinetic simulations of reconnection-mediated turbulent flares in a magnetized electron-positron plasma, with weak and strong radiative cooling. Such flares can be generated around neutron stars and accreting black holes. We focus on the magnetically dominated regime where tension of the background magnetic field lines exceeds the plasma rest-mass density by a factor σ 0 > 1. In the simulations, turbulence is excited on a macroscopic scale l 0, and we observe that it develops by forming thin, dynamic current sheets on various scales. The deposited macroscopic energy dissipates by energizing thermal and nonthermal particles. The particle energy distribution is shaped by impulsive acceleration in reconnecting current sheets, gradual stochastic acceleration, and radiative losses. We parameterize radiative cooling by the ratio  of light-crossing time l 0/c to a cooling timescale, and study the effect of increasing  on the flare. When radiative losses are sufficiently weak,  < σ 0 − 1 , the produced emission is dominated by stochastically accelerated particles, and the radiative power depends logarithmically on  . The resulting radiation spectrum of the flare is broad and anisotropic. In the strong-cooling regime,  > σ 0 − 1 , stochastic acceleration is suppressed, while impulsive acceleration in the current sheets continues to operate. As  increases further, the emission becomes dominated by thermal particles. Our simulations offer a new tool to study particle acceleration by turbulence, especially at high energies, where cooling competes with acceleration. We find that the particle distribution is influenced by strong intermittency of dissipation, and stochastic acceleration cannot be described by a universal diffusion coefficient.

Modulational Instability of Ultraintense Laser Pulses in Magnetized Electron–Positron Plasmas

The modulational instability of ultraintense laser pulses in magnetized electron–positron plasmas is investigated in the present study. The equations for describing the interaction of ultraintense ...

Stability analysis and applications of traveling wave solutions of three-dimensional nonlinear modified Zakharov–Kuznetsov equation in a magnetized plasma

Propagation of three-dimensional nonlinear solitary waves in a magnetized electron–positron plasma is analyzed. Modified extended mapping method is further modified and applied to three-dimensional nonlinear modified Zakharov–Kuznetsov equation to find traveling solitary wave solutions. As a result, electrostatic field potential, electric field, magnetic field and quantum statistical pressure are obtained with the aid of Mathematica. The new exact solitary wave solutions are obtained in different forms such as periodic, kink and anti-kink, dark soliton, bright soliton, bright and dark solitary waves, etc. The results are expressed in the forms of trigonometric, hyperbolic, rational and exponential functions. The electrostatic field potential and electric and magnetic fields are shown graphically. The soliton stability of these solitary wave solutions is analyzed. These results demonstrate the efficiency and precision of the method that can be applied to many other mathematical physical problems.

Electrostatic solitons and Alfvén waves generated by streaming instability in electron-positron plasmas.

Electron-positron plasmas may be present in laboratory experiments and certain astrophysical environments. Due to the inertia symmetry there have been some debates about whether the nonlinear electrostatic solitons generated easily in electron-proton plasmas may develop in electron-positron plasmas. In this study we show the formation of electrostatic solitons and electromagnetic Alfvén waves in extensive magnetized electron-positron plasma system generated by streaming instabilities based on electromagnetic particle simulations along with fluid theory analyses. In particular, the four-component beam-plasma system may lead to the formation of interlacing electron and positron solitons in the early evolution stage (say, t<20ω_{p}^{-1}, where ω_{p}^{} is the plasma frequency) and large-amplitude Alfvén waves in the later phase (say, t>150ω_{p}^{-1}). The magnetic-field perturbations are generated by the beam and firehose-type instabilities associated with temperature anisotropy of T_{∥}>T_{⊥} resulting from the parallel plasma heating by the electrostatic instability. It is shown that the growth rates and the dominant wavelengths of both electrostatic and electromagnetic instabilities are consistent with the fluid theory. The coexistence of electrostatic solitons and electromagnetic Alfvén waves with significant magnetic field fluctuations in the same system is a unique feature of electron-positron plasmas and the unified theory behind the formation mechanisms is well addressed in the paper.

Fast magnetohydrodynamic cnoidal waves and solitons in electron-positron plasma

Linear and nonlinear propagation of fast magnetohydrodynamic waves (or magnetoacoustic waves) are studied in homogeneous, magnetized and warm collisionless electron-positron (e-p) plasma by using two fluid magnetohydrodynamic model. In the linear limit, the wave dispersion relation is obtained and wave dispersion effect which appears through inertial length in e-p plasma system is also discussed. Using reductive perturbation method, the Korteweg-de Vries (KdV) equation for small but finite wave amplitude of magnetoacoustic waves is derived with appropriate boundary conditions. The cnoidal wave and soliton solutions are obtained using well known Sagdeev potential approach for magnetoacoustic waves in e-p plasmas propagating in the direction perpendicular to the external magnetic field. The phase portrait analysis and numerical illustration of magnetoacoustic cnoidal waves and solitons is also presented by using the parameters such as magnetic field intensity, plasma density and temperature of electron and positron fluids for astrophysical plasma situations exist in the literature.

Acoustic solitons in a magnetized quantum electron-positron-ion plasma with relativistic degenerate electrons and positrons pressure

The obliquely nonlinear acoustic solitary propagation in a relativistically quantum magnetized electron-positron (e-p) plasma in the presence of the external magnetic field as well as the stationary ions for neutralizing the plasma background was studied. By considering the dynamic of the fluid e-p quantum and by using the quantum hydrodynamics model and the standard reductive perturbation technique, the Zakharov-Kuznetsov (ZK) equation is derived for small but finite amplitude waves and the solitary wave solution for the parameters relevant to dense astrophysical objects such as white dwarf stars is obtained. The numerical results show that the relativistic effects lead to propagate the electrostatic bell shape structures in quantum e-p plasmas like those in classical pair-ion or pair species for relativistic plasmas. It is also observed that by increasing the relativistic effects, the amplitude and width of the e-p acoustic solitary wave will decrease. In addition, the wave amplitude increases as positron density decreases in magnetized e-p plasmas. It is indicated that by increasing the strength of the magnetic field, the width of the soliton reduces and it becomes sharper. At the end, we have analytically and numerically shown that the pulse soliton solution of the ZK equation is unstable and have traced the dependence of the instability growth rate on electron density. It is found that by considering the relativistic pressure, the instability of the soliton pulse can be reduced. The results can be useful to study the obliquely nonlinear propagation of small amplitude localized structures in magnetized quantum e-p plasmas and be applicable to understand the particle and energy transport mechanism in compact stars such as white dwarfs, where the effects of relativistic electron degeneracy become important.

Elliptically polarized electromagnetic waves in a magnetized quantum electron-positron plasma with effects of exchange-correlation

The dispersion properties of elliptically polarized electromagnetic waves in a magnetized electron-positron-pair (EP-pair) plasma are studied with the effects of particle dispersion associated with the Bohm potential, the Fermi degenerate pressure, and the exchange-correlation force. Two possible modes of the extraordinary or X wave, modified by these quantum effects, are identified and their propagation characteristics are investigated numerically. It is shown that the upper-hybrid frequency and the cutoff and resonance frequencies are no longer constants but are dispersive due to these quantum effects. It is found that the particle dispersion and the exchange-correlation force can have different dominating roles on each other depending on whether the X waves are of short or long wavelengths (in comparison with the Fermi Debye length). The present investigation should be useful for understanding the collective behaviors of EP plasma oscillations and the propagation of extraordinary waves in magnetized dense EP-pair plasmas.

Influence of Spin on the Dispersion of a Massive Dirac Neutrino in a Magnetized Plasma

The dispersion law and the anomalous magnetic moment of a neutrino in a magnetized electron-positron plasma are investigated as functions of the magnetic field strength, the polarization state, energy, direction of motion, and mass of the neutrino, and the parameters of the plasma. The calculation was performed by the method of the time Green’s functions at finite temperature. Results for a massive neutrino in the limiting case are compared with the results of other authors, obtained earlier for a massless left-handed neutrino.

Stability analysis solutions for nonlinear three-dimensional modified Korteweg–de Vries–Zakharov–Kuznetsov equation in a magnetized electron–positron plasma

The nonlinear three-dimensional modified Korteweg–de Vries–Zakharov–Kuznetsov ​(mKdV–ZK) equation governs the behavior of weakly nonlinear ion-acoustic waves in magnetized electron–positron plasma which consists of equal hot and cool components of each species. By using the reductive perturbation procedure leads to a mKdV–ZK equation governing the oblique propagation of nonlinear electrostatic modes. The stability of solitary traveling wave solutions of the mKdV–ZK equation to three-dimensional long-wavelength perturbations is investigated. We found the electrostatic field potential and electric field in form traveling wave solutions for three-dimensional mKdV–ZK equation. The solutions for the mKdV–ZK equation are obtained precisely and efficiency of the method can be demonstrated.

Neutrino Spin and Dispersion in Magnetized Medium

The full energy shift of a massive Dirac neutrino in magnetized electron-positron plasma was investigated using the Matsubara imaginary time and real time formalisms. The neutrino dispersion in the magnetized medium was analyzed as a function of the neutrino spin and mass. It was shown that in a superstrong magnetic field the CP-symmetric plasma contribution to the neutrino energy greatly exceeds the analogous correction in the field-free case. The contribution of plasma to the anomalous magnetic moment of a neutrino was obtained.

Propagation of localized structures in relativistic magnetized electron-positron plasmas using particle-in-cell simulations

We use a particle-in-cell simulation to study the propagation of localized structures in a magnetized electron-positron plasma with relativistic finite temperature. We use as initial condition for the simulation an envelope soliton solution of the nonlinear Schrödinger equation, derived from the relativistic two fluid equations in the strongly magnetized limit. This envelope soliton turns out not to be a stable solution for the simulation and splits in two localized structures propagating in opposite directions. However, these two localized structures exhibit a soliton-like behavior, as they keep their profile after they collide with each other due to the periodic boundary conditions. We also observe the formation of localized structures in the evolution of a spatially uniform circularly polarized Alfvén wave. In both cases, the localized structures propagate with an amplitude independent velocity.

Hydrodynamic and kinetic models for spin-1/2 electron-positron quantum plasmas: Annihilation interaction, helicity conservation, and wave dispersion in magnetized plasmas

We discuss the complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider the contribution of the annihilation interaction in the quantum hydrodynamic equations and in the spectrum of waves in magnetized electron-positron plasmas. We consider the propagation of waves parallel and perpendicular to an external magnetic field. We also consider the oblique propagation of longitudinal waves. We derive the set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory to the linear wave behavior in absence of external fields. We calculate the contribution of the Darwin and annihilation interactions in the Landau damping of the Langmuir waves. We should mention that the annihilation interaction does not change number of particles in the system. It does not related to annihilation itself, but it exists as a result of interaction of an electron-positron pair via conversion of the pair into virtual photon. A pair of the non-linear Schrodinger equations for the electron-positron plasmas including the Darwin and annihilation interactions is derived. Existence of the conserving helicity in electron-positron quantum plasmas of spinning particles with the Darwin and annihilation interactions is demonstrated. We show that the annihilation interaction plays an important role in the quantum electron-positron plasmas giving the contribution of the same magnitude as the spin-spin interaction.

Solitary waves in rotational pulsar magnetosphere

The nonlinear propagation of intense electromagnetic waves and modulational instability in a rotational ultra-relativistic magnetized electron-positron plasma of a pulsar magnetosphere have been theoretically investigated by deriving and solving nonlinear Schrodinger equation. It has found that the electromagnetic waves propagation in such a plasma system are modulationally unstable, and the model leads to electromagnetic solitons under the condition of extreme rotation. It is noticed that high amplitude solitons are produced in the pulsar magnetosphere. It is also found that the solitons amplitude increased rapidly while their widths become narrower with the increased of pulsar rotation that are related to the pulsar radiation (electromagnetic radiation). The solitons that may exist in pulsar magnetosphere are briefly discussed.

Linear and nonlinear electromagnetic waves in a magnetized quantum electron-positron plasma

The linear and nonlinear properties of the electromagnetic waves are investigated in a magnetized quantum electron–positron (e–p) plasma by employing the quantum hydrodynamic (QHD) model. It is found that the quantum dispersion relation in comparison with the classical version is modified by the quantum corrections through quantum diffraction and statistics. The standard reductive perturbation technique is used to derive the Korteweg–de Vries (KdV) equation. The exact soliton solutions and the existence regions of the solitary waves are also defined precisely. It is also shown that the results are affected by the quantum corrections.