Cold Positrons Research Articles

On the positron-acoustic Kawahara solitary and cnoidal waves in a non-Maxwellian electron–positron–ion plasma

The dissemination of positron-acoustic (PA) nonlinear structures, including the solitary waves (SWs) and cnoidal waves (CWs), is analyzed in an unmagnetized electron–positron–ion (e–p–i) plasma having inertial cold positrons and inertialess Cairns distributed electrons and Maxwellian positrons as well as immobile positive ions. The reductive perturbation method (RPM) is introduced to reduce the fluid equations to this model to the Korteweg–de Vries (KdV) type equation for studying small amplitude PA waves (PAWs). Moreover, the Kawahara (sometimes called the fifth-order KdV) equation is also obtained to investigate the characteristics of large amplitude PAWs. The effects of related parameters, such as nonthermal parameters, hot positron concentration, electron concentration, and temperature ratios, are numerically examined on the features of SWs and CWs.

Propagation of collisional among multi-soliton, multi-singular solition and rogue wave around the critical values in an unmagetized plasma

Progress in understanding the propagation characteristics of (i) collisional acoustic among multi-soliton and multi-singular soliton around the critical values and their corresponding phase shifts and (ii) collision between two rogue waves (RWs) propagating toward each in a plasma environment is presented. The considered plasma environment consists of mobile cold positrons, immobile positive ions and (r, q)-distributed hot positrons, and electrons. To accomplish our goal, the coupled modified Korteweg–de Vries equations (mKdVEs) and nonlinear Schrödinger equations (NLSEs) are derived from the considered plasma environment. Based on the concept of Hirota's bilinear method, the multi-soliton and multi-singular soliton solutions of the coupled mKdVEs are determined directly. In addition, the analytical unstable RWs solutions of the coupled NLSEs are determined. With the impact of physical parameters, (i) the trajectories are described for double, triple, quadruple and quintuple positron acoustic bi-directional multi-soliton and (ii) the variation of collisional RWs profiles are displayed with physical interpretation. The results described by the coupled mKdVEs also show that the scattered double-, triple-, quadruple-, and quintuple-soliton are elastic and preserved their original features oppositely after the collision around the critical value of any specific plasma parameter.

Dynamic behavior of positron acoustic multiple-solitons in an electron–positron-ion plasma

We explore the dynamic characteristics of positron acoustic multiple-solitons in an unmagnetized plasma containing mobile cold positrons, Kappa-distributed superthermal hot electrons and positrons, and stationary positive ions. This study investigates the overtaking collisional effects, various parametric impacts, and phase shifts in the electron–positron-ion (e-p-i) plasma. Through the reductive perturbation technique, we derived the Korteweg-de Vries (KdV) equation and the modified Korteweg-de Vries (mKdV) equation. The multiple-soliton solutions (MSS) are then obtained using the simplified Hirota method and Cole-Holf transformation. The investigation shows that the amplitudes and widths of multi-solitons decrease with the increasing hot positron concentration but increase with the increasing hot electron index parameter. The results are expected to help us understand the dynamics of waves propagation in the pulsar magnetosphere, the active galactic nuclei, the quasar’s relativistic jet, the inner region of the accretion disk surrounding a black hole, etc.

Interaction of two soliton waves in plasma including electrons with Kappa-Cairns distribution function

• The nonlinear propagation of soliton waves can be expressed by different equations. • KdV equation includes the equilibrium between nonlinearity and dispersion sentences, which gives information about the soliton waves. • One of the distribution functions that has been utilized in the last few years is the C-T distribution function. • The results demonstrated that the parameters and have a great impact on phase. velocity, nonlinear and dispersive coefficients, Sagdeev potential, maximum amplitude, and width of IASWs. a q The interaction of positron acoustic soliton waves (PASWs) with the arbitrary collision angle in plasma including cold fluid positrons, stationary ions and electrons with Kappa-Cairns (K-C) distribution function have been studied. The equations of Korteweg-de Vries (KdV) and the phase shifts are obtained by employing the extended Poincaré–Lighthill–Kuo (PLK) method for the two colliding waves. The influences of parameters of the K-C distribution function ( κ and α ), the collision angle θ and the proportion of the ion (electron) and positron unperturbed densities ( β i ( β e )) on the phase shifts are investigated.

Collisional positron acoustic soliton and double layer in an unmagnetized plasma having multi-species

This paper explores the head-on collision between two-counter propagating positron acoustic solitons and double layers (DLs) in an unmagnetized collisionless plasma having mobile cold positrons fluid, immobile positive ions and (r,;q)-distributed hot positrons, and hot electrons. By employing the extended Poincaré–Lighthill–Kuo method, the coupled Korteweg–de Vries (KdV), modified KdV (mKdV) and Gardner equations are derived to archive this goal. The effect of dimensionless parameters on the propagation characteristics of interacting KdV solitons (KdVSs), mKdV solitons (mKdVSs), Gardner solitons (GSs) and DLs are examined in detail by considering the limiting cases of (r,;q)-distribution. It is noted that the interaction of GSs and DLs are reported for the first time. The outcomes might be comprehended and beneficial not only in space and astrophysical environments but also in laboratory studies.

The ion acoustic solitary waves in the four-component complex plasma with a Cairns-Tsallis distribution

We study the ion acoustic solitary waves in the four-component complex plasma consisting of cold inertial ions, positrons, cold and hot (two-temperature) electrons, where the electrons and positrons are a Cairns-Tsallis distribution and have different nonthermal and nonextensive parameters. Base on the plasma hydrodynamic equations and Sagdeev pseudo-potential theory, we derive the conditions of the solitary waves to exist in the plasma, such as the Sagdeev pseudo- potential, the normalized electrostatic potential, the lower and upper limits of Mach number, and the compressive/rarefactive solitary wave. We show that, according to the present study, the solitary wave solutions exist only if the positrons are a Maxwellian distribution and the two-temperature electrons have the same nonextensive and nonthermal parameters. Numerical analyses are made for the conditions of solitary waves depending on the nonextensive and nonthermal parameters in the Cairns-Tsallis distribution.

On the binding energies of antihydrogen formed by the interactions of antiprotons in cold positron plasmas

The binding energies of antihydrogen atoms formed when antiprotons are mixed with positron plasmas having densities ranging from 1013–1015 m−3, and at temperatures of 5–30 K, have been investigated using simulations. Major changes in the distribution of binding energies are observed, with more strongly bound states evident at the higher densities, and at lower temperatures. For deeper binding, the distribution of binding energies follows a power-law which is found to be strongly dependent upon plasma properties and the strength of the applied magnetic field. The underpinning role of collisions in determining the binding energies is explored.

Positron-acoustic traveling waves solutions and quasi-periodic route to chaos in magnetoplasmas featuring Cairns nonthermal distribution

Dynamics of the positron acoustic waves (PAWs) in magnetoplasmas following Cairns non-thermal distribution is studied on the frameworks of the Korteweg–de Vries (KdV) and modified Korteweg–de Vries (mKdV) equations. The reductive perturbation technique is used to derive the KdV and mKdV equations. Bifurcations of positron acoustic traveling waves of these equations are addressed by employing the bifurcation theory of planar dynamical systems. It is found that the KdV equation supports compressive positron acoustic solitary waves (PASWs), while the mKdV equation supports both compressive and rarefactive PASWs. Using numerical simulations, effect of the nonthermal parameter ( $$\beta $$ ), temperature ratio of hot electron to hot positron ( $$\sigma $$ ), magnetic field ( $$\omega _{c_{1}}$$ ), ratio of hot electron to cold positron concentration ( $$\mu _{e}$$ ), and ratio of hot to cold positron concentration ( $$\mu _{p}$$ ) are discussed on the PASWs solutions of the KdV and mKdV equations. The criterion of chaos for these perturbed equations under the external periodic perturbation are obtained through quasi-periodic route to chaos. It is in fact shown that transition to chaos in our system depends on the frequency $$\omega $$ and the strength of the external periodic perturbation $$f_{0}$$ . These parameters control the dynamic behavior of the PAWs. The relevance of this work may be useful to understand the qualitative changes in the dynamics of perturbed PAWs appearing in auroral acceleration region as well as the astrophysical and laboratory plasma, where static external magnetic field and nonthermal parameter are present.

Twisted positron-acoustic wave in quantum plasmas

In this paper, we explore the existence of positron-acoustic wave (PAW) carrying orbital angular momentum (OAM) in a quantum electron-positron-ion (EPI) plasma system containing electrons, two-temperature positrons, and immobile ions as a neutralizing background. To achieve this aim, we employ the quantum hydrodynamic approach to obtain the evaluation equation of cold positrons density. By solving this equation in the paraxial limit, the Laguerre–Gaussian (LG) modes of positron perturbation are derived, and their corresponding angular momentum densities are calculated. In the following, based on numerical analyses it is found that the evolution of LG potentials and cold positrons density oscillations are greatly affected by variation of radial and angular mode numbers, relative Fermi temperature of hot species, positrons concentration, and azimuthal phase value. It is expected that the results of this study will give more insight into the positrons dynamics in dense astrophysical and laboratory plasmas.

Solitary dispersive Alfven wave in a plasma with hot electrons, cold positrons and ions

The dispersion relation and the nonlinear behaviour of dispersive Alfven waves (DAWs) in a plasma, which is composed by hot electrons, cold positrons and ions, are studied from the multi-component fluid theory. It can be indicated from the linear dispersion relation that the coupling of positron acoustic waves with shear Alfven waves results from the effect of the finite ion gyroradius. In our mode, the pressure and the inertia of the positron acoustic wave are, respectively, provided by the hot electrons and the cold positrons, which are different from the ones in a plasma consisting of two-group positrons with different temperatures. Furthermore, the existence and properties of DAW solitons are analysed from the Sagdeev pseudopotential equation, which indicates the existence of super-Alfvenic or sub-Alfvenic solitary DAWs, as well as the amplitude and width of DAW solitons depend on the positron concentration and the electron temperature. When the effects of cold positrons can’t be neglected, there may coexist the compressive and rarefactive DAW solitons. When the concentration of positron is negligibly small, the properties of DAW solitons in our model are similar to the ones of kinetic Alfven wave solitons in a plasma composed by hot electrons and cold ions.

Modulated positron-acoustic waves and rogue waves in a magnetized plasma system with nonthermal electrons and positrons

A theoretical and numerical study on amplitude modulated positron-acoustic waves (PAWs) in a magnetized four-component space plasma (containing immobile positive ions, inertial cold positrons, and inertia-less hot electrons and positrons following Cairn’s non-thermal distribution function) has been carried out. The reductive perturbation method have been applied to derive the corresponding nonlinear Schrodinger (NLS) equation, whose the nonlinear and dispersion coefficients $Q$ and $P$ are function of the external magnetic field. The criteria for the occurrence of modulational instability (MI) of PAWs is addressed. It is shown that the plasma parameters contribute to enhance substantially the growth rate and the bandwidth of the MI. It is also found from the analysis of the NLS equation that the plasma system under assumption supports the existence of Peregrine solitons and super-rogue waves, whose amplitude are significantly modified by the effects of the external magnetic field, the density ratio of hot positron and cold positron, the density ratio of electron and cold positron, and the non-thermal parameter. Moreover, the various types of localized positron-acoustic excitations exist in the form of bright envelope soliton and dark envelope soliton. It is found that the localized structures’s properties (width and amplitude) are influenced by the presence of magnetic field. The relevance of present study can help researchers to explain the various localized structures and the basic features of PAWs in a magnetized plasmas environments.

Effect of Anisotropic Pressure on Electron Acoustic Oscillatory and Monotonic Shocks in Superthermal Magnetoplasma

AbstractNonlinear oscillatory and monotonic electron acoustic shock waves in dissipative magnetorotating electron‐positron‐ion plasmas containing cold dynamical electrons, superthermal electrons, and positrons have been analyzed in the stationary background of massive positive ions. The Korteweg de‐Vries‐Burgers equation which describes the dynamics of the nonlinear shock structures is derived by using amplitude reductive perturbation technique. The quantitative analysis of impact of different physical parameters on the shock structures is presented here. The electron fluid viscosity plays a pivotal role for the transition of electron acoustic (EA) monotonic to oscillatory shocks and vice versa. It is remarkable that the shock structures are sensitive to the Coriolis force, obliqueness, electron temperature, and the positrons concentration. The present work may be employed to explore and to understand the formation of electron acoustic shock structures in the space and laboratory plasmas with superthermal electrons and positrons under magnetorotating effects, especially in auroral zone, Van Allen radiation belts, planetary magnetospheres, pulsars, black‐hole magnetospheres, etc.

Propagation of Solitary Waves and Double-Layers in Electron–Positron Pair Plasmas with Stationary Ions and Nonextensive Electrons

Based on reductive perturbation theory, the nonlinear structure of non-extensive multispecies plasma containing hot electrons, adiabatic cold electrons, cold positrons and ions has been investigated via different nonlinear KdV, mKdV and Gardner’s equations. It is shown that the formation and properties of electron acoustic solitary waves and double-layer can exist in such plasma system depending on some relevant physical parameters such as electron and positron density ratios, electrons temperatures ratio and non-extensive parameter. The existence conditions of these types of waves are extensively discussed. The obtained results may be useful in improving and understanding the propagation of the nonlinear electron waves in space plasma, Earth’s magnetosphere and solar wind.

Theoretical analysis of planar and non‐planar electron ‐ acoustic shock waves in electron‐positron‐ion plasma

The propagation properties of planar and non‐planar electron acoustic shock waves composed of stationary ions, cold electrons, and q‐non‐extensive hot electrons and positrons are studied in unmagnetized electron‐positron‐ion plasma. In this model, the Korteweg‐de Vries Burgers equation is obtained in the planar and non‐planar coordinates. We have investigated the combined action of the dissipation, non‐extensivity, density ratio of hot to cold electrons, concentration of positrons, and temperature difference of cold electrons, hot electrons, and positrons. It was found that the amplitude of shock wave in e‐p‐i plasma increases when the positron concentration and temperature increase. The same effect is observed in the case of kinematic viscosity η. Furthermore, it is noticed that spherical wave moves faster in comparison to the shock waves in cylindrical geometry. This difference arises due to the presence of the geometry term m/2τ. It should be noted that the contribution of the geometry factor comes through the continuity equation. Results of our work may be helpful to illustrate the different properties of shock wave features in different astrophysical and space environments like supernova, polar regions, and in the vicinity of black holes.

Dynamical Behavior of Supernonlinear Positron-Acoustic Periodic Waves and Chaos in Nonextensive Electron-Positron-Ion Plasmas

Abstract Propagation of nonlinear and supernonlinear positron-acoustic periodic waves is examined in an electron-positron-ion plasma composed of static positive ions, mobile cold positrons, and q-nonextensive electrons and hot positrons. Employing the phase plane theory of planar dynamical systems, all qualitatively different phase portraits that include nonlinear positron-acoustic homoclinic orbit, nonlinear positron-acoustic periodic orbit, supernonlinear positron-acoustic homoclinic orbit, and supernonlinear positron-acoustic periodic orbit are demonstrated subjected to the parameters q , μ 1 , μ 2 , σ 1 , σ 2 $q,{\mu_{1}},{\mu_{2}},{\sigma_{1}},{\sigma_{2}}$ , and V. The nonlinear and supernonlinear positron-acoustic periodic wave solutions are reported for different situations through numerical computations. It is observed that the nonextensive parameter (q) acts as a controlling parameter in the dynamic motion of nonlinear and supernonlinear positron-acoustic periodic waves. The dynamic motions for the positron-acoustic traveling waves with the influence of an extrinsic periodic force are investigated through distinct qualitative approaches, such as phase portrait analysis, sensitivity analysis, time series analysis, and Poincaré section. The results of this paper may be applicable in understanding nonlinear, supernonlinear positron-acoustic periodic waves, and their chaotic motion in space plasma environments.

Head-on collision between positron acoustic waves in homogeneous and inhomogeneous plasmas

The head-on collision between positron acoustic solitary waves (PASWs) as well as the production of rogue waves (RWs) in homogeneous and PASWs in inhomogeneous unmagnetized plasma systems are investigated deriving the nonlinear evolution equations. The plasmas are composed of immobile positive ions, mobile cold and hot positrons, and hot electrons, where the hot positrons and hot electrons are assumed to follow the Kappa distributions. The evolution equations are derived using the appropriate coordinate transformation and the reductive perturbation technique. The effects of concentrations, kappa parameters of hot electrons and positrons, and temperature ratios on the characteristics of PASWs and RWs are examined. It is found that the kappa parameters and temperature ratios significantly modify phase shifts after head-on collisions and RWs in homogeneous as well as PASWs in inhomogeneous plasmas. The amplitudes of the PASWs in inhomogeneous plasmas are diminished with increasing kappa parameters, concentration and temperature ratios. Further, the amplitudes of RWs are reduced with increasing charged particles concentration, while it enhances with increasing kappa- and temperature parameters. Besides, the compressive and rarefactive solitons are produced at critical densities from KdV equation for hot and cold positrons, while the compressive solitons are only produced from mKdV equation for both in homogeneous and inhomogeneous plasmas.

Modulational instability and generation of envelope solitons in four‐component space plasmas

The four‐component space plasma (containing immobile positive ions, inertial cold positrons, and inertia‐less hot electrons and positrons following Cairns' non‐thermal distribution function) is considered. The modulational instability and the generation of positron‐acoustic (PA) envelope solitons in such a space plasma system are investigated by deriving the non‐linear Schrödinger (NLS) equation. It is found from the numerical analysis of the NLS equation that the plasma system under consideration supports the existence of both dark and bright envelope solitons associated with the PA waves. It is also observed that the instability criterion and the growth rate of the unstable PA waves are significantly modified by the plasma parameters (i.e. temperature and number density of different plasma species). The implications of the results to space plasma research are briefly discussed.

Qualitative analysis of the positron-acoustic waves in electron-positron-ion plasmas with κ deformed Kaniadakis distributed electrons and hot positrons

Qualitative analysis of the positron acoustic (PA) waves in a four-component plasma system consisting of static positive ions, mobile cold positron, and Kaniadakis distributed hot positrons and electrons is investigated. Using the reductive perturbation technique, the Korteweg-de Vries (K-dV) equation and the modified KdV equation are derived for the PA waves. Variations of the total energy of the conservative systems corresponding to the KdV and mKdV equations are presented. Applying numerical computations, effect of parameter (κ), number density ratio (μ1) of electrons to ions and number density (μ2) of hot positrons to ions, and speed (U) of the traveling wave are discussed on the positron acoustic solitary wave solutions of the KdV and mKdV equations. Furthermore, it is found that the parameter κ has no effect on the solitary wave solution of the KdV equation, whereas it has significant effect on the solitary wave solution of the modified KdV equation. Considering an external periodic perturbation, the perturbed dynamical systems corresponding to the KdV and mKdV equations are analyzed by employing three dimensional phase portrait analysis, time series analysis, and Poincare section. Chaotic motions of the perturbed PA waves occur through the quasiperiodic route to chaos.

Nonlinear excitations for the positron acoustic waves in auroral acceleration regions

Positron acoustic waves (PAWs) in an unmagnetized electron-positron-ion (e-p-i) plasma consisting of mobile cold positrons, immobile positive ions, q-nonextensive distributed electrons and hot positrons are studied. The standard reductive perturbation technique (RPT) is applied to derive the Kurteweg-de Vries (KdV) and modified Kurteweg-de Vries (mKdV) equations for PAWs. Variations of the total energy of the conservative systems corresponding to the KdV and mKdV equations are presented. Using numerical simulations, effect of the nonextensive parameter (q), temperature ratio (σ) of electrons to hot positrons and speed (U) of the traveling wave are discussed on the positron acoustic solitary wave solutions of the KdV and mKdV equations. Considering an external periodic perturbation, the perturbed dynamical systems corresponding to the KdV and mKdV equations are analyzed by employing phase orbit analysis, Poincare section and Lyapunov exponent. The frequency (ω) of the external periodic perturbation plays the role of the switching parameter in chaotic motions of the perturbed PAWs through quasiperiodic route to chaos. This work may be useful to understand the qualitative changes in the dynamics of nonlinear perturbations in auroral acceleration regions.

Nonlinear Propagation of Positron-Acoustic Periodic Travelling Waves in a Magnetoplasma with Superthermal Electrons and Positrons

The nonlinear propagation of positron acoustic periodic (PAP) travelling waves in a magnetoplasma composed of dynamic cold positrons, superthermal kappa distributed hot positrons and electrons, and stationary positive ions is examined. The reductive perturbation technique is employed to derive a nonlinear Zakharov–Kuznetsov equation that governs the essential features of nonlinear PAP travelling waves. Moreover, the bifurcation theory is used to investigate the propagation of nonlinear PAP periodic travelling wave solutions. It is found that kappa distributed hot positrons and electrons provide only the possibility of existence of nonlinear compressive PAP travelling waves. It is observed that the superthermality of hot positrons, the concentrations of superthermal electrons and positrons, the positron cyclotron frequency, the direction cosines of wave vector k along the z-axis, and the concentration of ions play pivotal roles in the nonlinear propagation of PAP travelling waves. The present investigation may be used to understand the formation of PAP structures in the space and laboratory plasmas with superthermal hot positrons and electrons.