Amplitude Ion-acoustic Solitary Waves Research Articles

Electron beam driven ion-acoustic solitary waves in plasmas with two kappa-distributed electrons

Formation and the basic features of arbitrary amplitude ion-acoustic solitary waves (IASWs) in a plasma consisting of warm positive ions, two kappa-distributed electrons and an electron beam are investigated by using the Sagdeev pseudopotential approach. It is shown that the soliton existence domain (Mach number limits) sensitively depends on temperature of ions, spectral index of cool electrons and concentration of hot electron species while spectral index of hot electrons, hot-to-cool electron temperature ratio and also concentration of electron beam do not considerably affect this domain. It is also found that temperature of electron beam only affect the existence domain of rarefactive solitons. Furthermore, it is shown that considered plasma medium supports the coexistence of positive and negative IASWs. Moreover, effect of different plasma parameters such as hot-to-cool electron density ratio, ion-to-cool electron temperature ratio, beam-to-ion density ratio, hot-to-cool electron temperature ratio and superthermality index of electron species on the basic features of positive and negative IASWs is investigated numerically. Finally, the effect of plasma parameters on the parametric regime of coexistence of compressive and rarefactive IASWs is studied and, for example, effect of temperature of positive ions and number density of hot electrons on polarity of IASWs is numerically investigated.

Small amplitude ion-acoustic solitary waves in a magnetized ion-beam plasma under the effect of ion and beam temperatures

Small amplitude ion-acoustic solitary waves in a magnetized ion-beam plasma under the effect of ion and beam temperatures

Small amplitude ion-acoustic solitary waves in a four-component magneto- rotating plasma with a modified Cairns-Tsallis distribution

The small amplitude ion-acoustic solitary waves in the magneto-rotating plasma consisting of cold fluid ions, hot positrons, and the two-temperature electrons (cold and hot electrons) are investigated when the electrons obey a modified Cairns-Tsallis distribution. By using the reductive perturbation method, we derive the Korteweg–de Vries equation and the modified Korteweg–de Vries equation and obtain the small amplitude ion-acoustic solitary wave solutions. The dependences of solitary wave solutions on the nonextensive q-parameter, the nonthermal α-parameter and the plasma physical quantities are analyzed numerically. We show the significant effects of the nonextensive q-parameter and the nonthermal α-parameter etc on the ion-acoustic solitary waves.

Ion-Acoustic Solitary Waves in a Partially Degenerate Plasma

The propagation of arbitrary amplitude ion-acoustic (IA) solitary waves (SWs) is studied in unmagnetized, collisionless, homogeneous electron-positron-ion (e-p-i) plasmas with finite temperature degeneracy of both electrons and positrons. Starting from a set of fluid equations for classical ions and Fermi-Dirac distribution for degenerate electrons and positrons, a linear dispersion relation for IA waves is derived. It is seen that the wave dispersion is significantly modified due to the presence of positron species and the effects of finite temperature degeneracy of electrons and positrons. In the nonlinear regime, the Sagdeev's pseudopotential approach is employed to study the existence domain and the evolution of nonlinear IA-SWs in terms of the parameters that are associated with the finite temperature degeneracy, the background number densities, and the thermal energies of electrons and positrons. It is found that in contrast to classical electron-ion plasmas both the subsonic and supersonic IA-SWs can exist in a partially degenerate e-p-i plasma.

Large amplitude ion-acoustic solitary waves in a warm negative ion plasma with superthermal electrons: The fast mode revisited

Large amplitude ion-acoustic fast mode solitary waves in a negative ion plasma with kappa electrons are revisited, using the Sagdeev pseudopotential approach. As is well known, this plasma supports the propagation of both compressive and rarefactive solitons, and there exist a range of parameter values in which the two types of structures coexist. This is confirmed by the present study, which is based on well-established soliton existence domains. After investigating the existence of solitons in terms of the lower and upper Mach number limits for broader regions in the parameter space, we have found that as a result of the ion thermal effects, the range of the allowed Mach numbers is reduced and only small amplitude rarefactive solitons propagate in this plasma, an effect that is enhanced by the superthermal behavior of the electrons. Rearranging our analytical work so as to get a two-positive ion plasma, our results show the presence of stopbands in the soliton existence domains, as reported by Nsengiyumva et al. [Phys. Plasmas 21, 102301 (2014)], despite the use of different normalization and different parameter space. This suggests that the observed stopbands are a real phenomenon, which needs consideration when studying plasma waves.

Oblique ion acoustic excitations in a magnetoplasma having $\kappa $-deformed Kaniadakis distributed electrons

In this paper, a very first use of the $\kappa $-deformed Kaniadakis distribution is made in the context of arbitrary amplitude ion-acoustic solitary waves (IASWs) in a magnetized plasma composed of cold fluid ions and non-Maxwellian electrons. The basic equations governing the dynamics of nonlinear structures are reduced to an evolution equation in the form of an energy-balance like equation through the use of the Sagdeev approach. The deformed average kinetic energy linked with electrons is calculated which restricts to narrow range the allowed values of the deformation parameter $\kappa $ that develops Kaniadakis entropy. As an application, we analyse the effect of $\kappa $ on the existence domain as well as on the characteristic behavior of IASWs. The effect of all other relevant plasma parameters (viz., Mach number, strength of magnetic field and obliqueness) is also discussed. The results of the present work may contribute significantly to the current research concerning the use of the generalized entropies in the context of plasma physics.

Shock wave generation in plasmas at varying magnetic field

By considering the continuity, the Navier-Stokes and Poisson's equations in a nonrelativistic framework for plasmas, we study the behavior of small amplitude ion acoustic solitary waves in plasmas under the influence of a varying magnetic field. The result is a nonlinear wave equation which complies with the modified Korteweg-de Vries-Burgers equation, surprisingly in the absence of thermal pressure or any dissipative effects. We show that the complete set of equations, by considering the varying magnetic field, creates solitary waves which radiate energy during their travel in the medium. An interesting result is the existence of small amplitude localized shock profiles beside the solitary waves. Properties of this solitaire solution are studied by considering different values for the environmental characters.

Effects of positive ion temperature and negative ion number density on arbitrary amplitude ion-acoustic solitary waves in nonextensive electronegative plasma

The formation and the basic features of arbitrary amplitude ion-acoustic solitary waves (IASWs) in an electronegative plasma containing cold negative ion fluid, warm positive ion fluid and nonextensive electrons are theoretically investigated by using the pseudo-potential technique. The pseudo-potential is analytically and numerically analyzed and the conditions for the formation of the arbitrary amplitude IASWs and their basic features (viz. polarity, amplitude, width etc.) are identified. It is observed that the electronegative plasma under consideration supports the coexistence of compressive and rarefactive IASWs, and that the temperatures and number density of positive ion fluid significantly modify not only the basic features of compressive and rarefactive IASWs, but also the parametric regime of their coexistence. The implications of our results in some space and laboratory electronegative plasma situations are finally pinpointed.

Particle-in-cell simulation of the head-on collision of large amplitude ion-acoustic solitary waves in a collisionless plasma

The head-on collision of ion-acoustic solitary waves in a collisionless plasma with cold ions and Boltzmann electrons is studied using the particle-in-cell (PIC) simulation. It is shown that solitary waves of sufficiently large amplitudes do not retain their identity after a collision. Their amplitudes decrease and their forms change. In the collision of solitary waves, accelerated ions are formed. The ion velocities can reach three speeds of sound. Dependences of amplitudes of the potential and densities of ions and electrons after a head-on collision of identical solitary waves on their initial amplitude are presented.

Arbitrary amplitude ion-acoustic solitary waves in a two-temperature nonextensive electron plasma

Effects of presence of ions on the existence and structure of arbitrary amplitude ion-acoustic solitary waves in a plasma consisting of thermal ions and two-temperature nonextensive electrons are investigated. It is shown that solitons of both polarity (compressive and rarefactive) can exist in such a plasma, depending on the range of the plasma parameters. Also, it is seen that the maximum amplitude and the width of both soliton types depend sensitively on the temperature and concentration of ions. To better understand the role of positive ions, the presented model is reduced to a Maxwellian plasma and the results are compared to their Maxwellian counterparts.

Arbitrary amplitude ion-acoustic solitary waves in electronegative plasmas with electrons featuring Tsallis distribution

The problem of arbitrary amplitude ion-acoustic solitary waves (IASWs), which accompany electronegative plasmas having positive ions, negative ions, and nonextensive electrons is addressed. The energy integral equation with a new Sagdeev potential is analyzed to examine the existence regions of the IASWs. Different types of electronegative plasmas inspired from the experimental studies of Ichiki et al. (2001) are discussed. Our results show that in such plasmas IASWs, the amplitude and nature of which depend sensitively on the mass and density ratio of the positive and negative ions as well as the q-nonextensive parameter, can exist. Interestingly, one finds that our plasma model supports the coexistence of smooth rarefactive and spiky compressive IASWs. Our results complement and provide new insights on previously published findings on this problem.

Arbitrary amplitude ion acoustic solitary waves and double layers in a magnetized auroral plasma with q-nonextensive electrons

Using the Sagdeev pseudo-potential technique, further investigation on the effect of nonextensive hot electrons on finite amplitude nonlinear low-frequency electrostatic waves in a magnetized two-component plasma have been reported in detail. The plasma model consists of cold ions fluid and nonextensively distributed electrons. The existence domain for the nonlinear structures have been established analytically and numerically. Apart from the compressive and rarefactive soliton solutions that have been reported earlier, the present investigation shows that double layer structures can be obtained for certain values of nonextensive electrons in the supersonic Mach number regime. The present results may provide an explanation for the observed nonlinear structures in the auroral region of the Earth’s magnetosphere.

Ion acoustic solitary waves and double layers in a plasma with two temperature electrons featuring Tsallis distribution

The propagation properties of large amplitude ion acoustic solitary waves (IASWs) are studied in a plasma containing cold fluid ions and multi-temperature electrons (cool and hot electrons) with nonextensive distribution. Employing Sagdeev pseudopotential method, an energy balance equation has been derived and from the expression for Sagdeev potential function, ion acoustic solitary waves and double layers are investigated numerically. The Mach number (lower and upper limits) for the existence of solitary structures is determined. Positive as well as negative polarity solitary structures are observed. Further, conditions for the existence of ion acoustic double layers (IADLs) are also determined numerically in the form of the critical values of qc, f and the Mach number (M). It is observed that the nonextensivity of electrons (via qc,h), concentration of electrons (via f) and temperature ratio of cold to hot electrons (via β) significantly influence the characteristics of ion acoustic solitary waves as well as double layers.

Re-examining the Cairns-Tsallis model for ion acoustic solitons

Recently, a hybrid distribution function [Tribeche et al., Phys. Rev. E 85, 037401 (2012)] was proposed to describe a plasma species with an enhanced superthermal component. This combines a Cairns-type "nonthermal" form with the Tsallis theory for nonextensive thermodynamics. Using this alternative model, the propagation of arbitrary amplitude ion acoustic solitary waves in a two-component plasma is investigated. From a careful study of the distribution function it is found that the model itself is valid only for a very restricted range in the q-nonextensive parameter and the nonthermality parameter, α. Solitary waves, the amplitude and nature of which depend sensitively on both q and α, can exist within a narrow range of allowable Mach numbers. Both positive and negative potential structures are found, and coexistence may occur.

Electrostatic wave structures in a magnetized superthermal plasma with two-temperature electrons

The linear and nonlinear excitation of arbitrary amplitude ion-acoustic (IA) solitary waves in a magnetized plasma comprising two-temperature electrons and cold ions are studied. The oblique propagation properties of two possible modes (in the linear regime) are investigated. It is found that the electron superthermality reduces the phase velocities of both modes, whereas obliqueness leads to an increase in the separation between two modes. In the nonlinear regime, an energy-like equation describes the evolution of IA solitary waves in the present model. The combined effects of the electron superthermality, magnitude of magnetic field, obliqueness and electron population are incorporated in the study of the existence domain of solitary waves and the soliton characteristics. It is shown that the small values of the hot electron population shift the permitted interval of Mach number to the lower values. Both compressive and rarefactive solitary structures are found to exist in the presence of two temperature electrons. The present investigation contributes to the physics of electrostatic wave structures in Saturn's magnetosphere in which two temperature electrons with kappa distribution exist.

Ion acoustic solitons in a nonextensive plasma with multi-temperature electrons

The properties of propagation of small amplitude ion acoustic solitary waves (IASWs) are studied in a plasma containing cold fluid ions and multi-temperature electrons (cool and hot electrons) with nonextensive distribution. Korteweg-de Vries (KdV) equation with finite amplitude is derived using a reductive perturbation method. From the solitary solutions of KdV equation, the combined effects of nonextensivity and density ratio are studied on characteristics of ion acoustic (IA) solitary waves. Positive as well as negative polarity solitons exist. Since singularity exists for A=0 so we have also derived modified Korteweg de Vries (mKdV) equation to study the solitonic solution for critical values of physical parameters (q,f,σ). The nonextensivity of electrons (via q) and density ratio of electrons and ions (via f) and temperature ratio (σ) significantly influence the characteristics of ion acoustic solitary structures.

Arbitrary Amplitude Ion Acoustic Solitary Waves in An Unmagnetized Two Electron Population Ultra-Relativistic Dense Plasmas

The nonlinear wave structure of arbitrary amplitude ion acoustic solitary waves (IASWs) are studied in the Sagdeev’s pseudopotential framework for an ultra-relativistic degenerate dense plasma comprising cold and hot electrons and inertial ultra-cold ions. By employing standard normal-mode analysis the dispersion relation for linear waves is studied. The numerical results are presented to understand the features of ion acoustic solitary wave structures. It is shown that the present plasma model supports IASWs having positive potential well. Also, it is found that the small amplitude rarefactive double layer solution can exist in such a plasma system in some parametric region. It is shown that solitary structures and double layers are affected by relevant plasma parameters.

Ion acoustic solitary waves in electron-positron-ion plasmas with q-nonextensive electrons and high relativistic ions

Propagation of small amplitude ion acoustic solitary waves in plasmas containing q-nonextensive electrons, thermal positrons and high relativistic ions is addressed in this paper. Our results show that the Korteweg-de Vries equation describes the nonlinear waves in such plasmas. The amplitude and the width of the solitons are derived and the effects of relativistic ions and q-nonextensive distribution of electrons on these quantities are discussed.

Nonlinear wave propagation of large amplitude ion-acoustic solitary waves in negative ion plasmas with superthermal electrons

AbstractInvestigation of arbitrary amplitude nonlinear ion-acoustic solitary waves which accompany collisionless positive–negative ion plasmas with high-energy electrons (represented by kappa distribution) is presented. Arbitrary amplitude solitary waves are investigated by deriving an energy-integral equation involving a Sagdeev-like pseudopotential. The existence regions of solitary pulses are, defined precisely, modified by the superthermality of energetic electrons. Furthermore, numerical calculations reveal that both compressive and rarefactive pulses may exist for negative ion mass groups in Titan's atmosphere. The superthermality of energetic electrons are found to modify the existence domains of large amplitude ion-acoustic waves in Titan's atmosphere. The dependence of solitary excitation characteristics on the superthermal parameter, the negative ion concentration, the positive-to-negative ions mass ratio, and the Mach number have been investigated. The present study might be helpful to understand the excitation of fully nonlinear ion-acoustic solitary pulses that may appear in the interplanetary medium and/or in the astrophysical plasmas in general.

Effect of ion temperature on ion-acoustic solitary waves in a plasma with a q-nonextensive electron velocity distribution

The effect of ion temperature on the existence of arbitrary amplitude ion-acoustic solitary waves is studied in a two component plasma in presence of a q-nonextensive velocity distributed electrons by using Sagdeev's pseudo potential technique. The range of relevent parameters for which solitons may exist is discussed. It is observed that both q, the nonextensive parameter and the ion temperature σ, play significant roles in the formation and existence of solitons.