Unmagnetized Plasma Research Articles

Investigating the nonlinear dynamics of acoustic waves by analyzing the Kadomtsev–Petviashvili equation in an unmagnetized plasma

This study explores the bifurcation analysis of ion-acoustic (IA) waves, electrostatic IA soliton propagation, as well as the behavior of periodic waves and chaos in a three-component, unmagnetized plasma composed of fully ionized ions and (r, q)-distributed electrons and positrons. To investigate the nonlinear behavior of IA waves across different plasma parameters, the Kadomtsev–Petviashvili equation is derived using the well-known reductive perturbation method. By applying a traveling wave transformation, a planar dynamical system is formulated. The phase portrait is then constructed to provide a detailed examination of the nonlinear wave phenomena emerging in the system. In addition, the Lyapunov spectrum is analyzed to determine whether the system exhibits chaotic motion. The impact of physical parameters on both the electrostatic and Sagdeev potentials is also studied. The findings of this research could contribute significantly to advancing the understanding of soliton propagation physics in astrophysical settings, various plasma environments, and laboratory experiments.

Propagation of envelope solitons in the presence of generalized (r; q) distribution of electrons

Abstract The study has been made for modulational instability of ion acoustic waves in an electron-ion unmagnetized plasma where ions are dynamic and warm while electrons follows the generalized (r,q) distribution. The Krylov Bogoliubov Mitropolsky (KBM) method is employed to derive the nonlinear Schrödinger equation (NLSE). The dispersive and nonlinear coefficients P and Q are retrieved which depend on σ_{i} (Temperature ratio) and spectral indices (r,q). The bright and dark solitons are excited for the case PQ>0 and PQ<0 respectively. Amplitude of bright solitons is characterized by a localized intensity peak and dark solitons by a localized intensity hole on a homogeneous background. The growth rates and modulationally stable/unstable zones are analyzed numerically. It is established that spectral indices (r,q) of electron distribution function and temperature ratio of ion to electron play a major role in the creation of bright/dark envelope solitons in electron-ion plasmas in the presence of nonthermal distribution.

Effect of combined Kappa-Cairns distributed electrons on modulational instability and envelope soliton of ion-acoustic waves in electron-ion dusty plasma

Abstract Theoretical and numerical investigations are performed to study the amplitude modulation of ion-acoustic waves in an unmagnetized collisionless dusty plasma system whose components are warm ions (adiabatic), charged (negative) dust particles and Combined Kappa-Cairns distributed electrons. Modulational instability of ion-acoustic waves is analyzed through derivation of the nonlinear Schrödinger equation using the reductive perturbation technique by implementing hydrodynamic equations for this system. The conditions for modulational instability for this electron-ion dusty plasma system have been developed, and the impacts of the relevant physical parameters on the instability region along with the maximum growth rate of instability are demonstrated. Bright and dark envelope solitons are presented, and it is observed that the profiles of envelope solitons are significantly influenced by the existence of high-energy Combined Kappa-Cairns distributed electrons.

Effect of combined Kappa-Cairns distributed electrons on modulational instability and envelope soliton of ion-acoustic waves in electron-ion dusty plasma

Abstract Theoretical and numerical investigations are performed to study the amplitude modulation of ion-acoustic waves in an unmagnetized collisionless dusty plasma system whose components are warm ions (adiabatic), charged (negative) dust particles and Combined Kappa-Cairns distributed electrons. Modulational instability of ion-acoustic waves is analyzed through derivation of the nonlinear Schr{"o}dinger equation using the reductive perturbation technique by implementing hydrodynamic equations for this system. The conditions for modulational instability for this electron-ion dusty plasma system have been developed, and the impacts of the relevant physical parameters on the instability region along with the maximum growth rate of instability are demonstrated. Bright and dark envelope solitons are presented, and it is observed that the profiles of envelope solitons are significantly influenced by the existence of high-energy Combined Kappa-Cairns distributed electrons.

Ion acoustic solitons and periodic waves with dynamical features around the supercritical values in relativistic unmagnetized plasmas

Ion acoustic solitons and periodic waves with dynamical features around the supercritical values in relativistic unmagnetized plasmas

Simulation of weak electron beam injection into plasma with open boundary conditions

Context. Different high-energy events lead to the generation of electron beams in the solar atmosphere as well as in planetary magnetospheres. The propagation of these beams through space plasma becomes a main source of non-thermal emission, primarily on the harmonics of the fundamental plasma frequency. Due to the high level of non-linearity and the complexity of such systems, theoretical studies of them are largely based on numerical simulations. However, it is still common practice to use a simplified model in which periodic boundary conditions for fields and particles are used to simulate an infinite plasma. Aims. In this work, the first attempt at high-resolution studies of the dynamics of a weak beam in space plasma using a model with open boundary conditions is reported. The general results of the simulations are compared with those obtained previously using the approximation of infinite plasma. Methods. The continuous injection of an electron beam with an average velocity of vb = 0.25c (c – speed of light) and a relative density of nb/n0 = 5 ⋅ 10−4 (n0 – plasma density) into an unmagnetised plasma was simulated in a quasi-1D approximation using a collisionless electromagnetic particle-in-cell code. The background plasma was initially homogeneous and consisted of electrons and protons with the real mass ratio. The total simulation time was 10 000 ωp0−1, where ωp0 is the Langmuir frequency for the given n0. Results. The present simulations demonstrate the formation of a spatially localised Langmuir turbulence in the close vicinity of the beam injection site. The continuous injection of fresh beam particles increases the amplitude of the plasma waves to values larger than those possible when simulating the same parameters in a simplified model. Plasma waves in this region turn out to be unstable against the modulation instability, so the formation of density wells followed by plasma wave trapping is observed. Some of the beam particles are significantly accelerated by previously arisen plasma waves. On average, only 10% of the beam energy gets lost in the system, but the distribution function is transformed into a flat-top form with a supra-thermal tail. Conclusions. The obtained results demonstrate several significant differences from the results of simulations using the approximation of infinite plasma. This fact emphasises the importance of using of a more realistic model for simulations of beam-plasma systems. In addition, using the model with open boundaries, in contrast to the simplified model, will allow us to correctly investigate the influence of not only random gradients of the plasma parameters, but also regular ones.

Dust acoustic soliton and shock structures with consequence of head-on collision in multi-component unmagnetized plasmas

Dust acoustic soliton and shock structures with consequence of head-on collision in multi-component unmagnetized plasmas

Exploring the dynamics of overtaking interactions of electron acoustic solitons in beam-driven unmagnetized plasmas: application in the auroral region

Abstract This study explores the propagation of nonlinear electron acoustic waves (EAWs) in an unmagnetized plasma consisting of dynamical inertial cold electrons, hot electrons following (r, q) distribution, a warm electron beam, and background ions. The fluid equations representing the plasma system are reduced to Kadomtsev–Petviashvili (KP) equation for EAWs by using the reductive perturbation technique. Our findings reveal that several key factors significantly influence the propagation and interaction properties of electron acoustic solitary waves (EASWs). These factors include the spectral indices r and q of the generalized (r, q) distribution, the concentrations of cold, hot, and beam electrons, as well as the temperature ratios among these electron populations. Additionally, we investigate the possible types of overtaking interactions between two Kadomtsev–Petviashvili (KP) solitons. The spatial regime for the interaction of two solitons is found to vary depending on the effect of plasma parameters on a single soliton behavior. This comprehensive analysis provides valuable insights into the complex interactions between EASWs, which are relevant for understanding phenomena in laboratory, space, and astrophysical plasmas.

Optical effects in unmagnetized cold plasmas by a chiral axion factor

Abstract Unmagnetized cold plasma modes are investigated in the context of the chiral Maxwell-Carroll-Field-Jackiw (MCFJ) electrodynamics, where the axion chiral factor acts retrieving some typical properties of magnetized plasmas. The Maxwell equations are rewritten for a cold, uniform, and collisionless fluid plasma model, allowing us to determine the dispersion relation, new refractive indices, and propagating modes. We find four distinct refractive indices modified by the purely timelike CFJ background that plays the magnetic conductivity chiral parameter role associated with right-circularly polarized (RCP) and left-circularly polarized (LCP) waves. For each refractive index, the propagation and absorption zones are determined and illustrated for some specific parameter values. Modified RCP and LCP helicons are found in the low-frequency regime. The optical behavior is investigated, revealing that the chiral factor induces birefringence, measured in terms of the rotatory power (RP). The dichroism coefficient is carried out for the absorbing zones. The negative refraction zones may enhance the involved RP, yielding RP sign reversion, a feature of rotating plasmas and MCFJ chiral plasmas. Charge density oscillations and Langmuir waves are also discussed, revealing no modified dispersion relation due to the chiral axion factor.

Nonlinear Ion-Acoustic Solitary Waves in a Weakly Relativistic Electron-Positron-Ion Plasma with Relativistic Electron and Positron Beams

In this investigation, compressive and rarefactive solitons are demonstrated to exist in a plasma model that includes unmagnetized weak-relativistic positive ions, negative ions, electrons, electron beam and positron beam. For these weakly relativistic non-linear ion-acoustic waves in unmagnetized plasma with electron inertia and relativistic beam, the existence of compressive and rarefactive soliton is investigated by deriving the Korteweg-de Vries (KdV) equation. It has been observed that the amplitude and width of compressive and rarefactive solitons vary differently in response to pressure variation and the presence of electron inertia. The research determines the requirements that must be met for the existence of the nonlinear ion-acoustic solitons. The fluid equations of motion governing the one-dimensional plasma serve as the foundation for the analysis. Various relational forms of the strength parameter (ε) are chosen to stretch the space and time variables, leading to a variety of nonlinearities. The findings can have implications not only for astrophysical plasmas but also for inertial confinement fusion plasmas.

Propagation Characteristics of Nonplanar Electron-Acoustic Waves in Non-Thermal Plasma

Abstract Nonplanar electron acoustic waves (NEAWs) having double spectral index distributed hot electrons are studied under two temperature electrons model in a collisionless unmagnetized plasma. Using this model, the Korteweg-de Vries (KdV) equation is derived in nonplanar geometry. On the basis of solutions of KdV equation, alteration of velocity, width and amplitude of acoustic waves having various plasma factors are investigated. Nonlinear and dispersion coefficients obtained rely on double spectral index parameters r and q, and particle density α. Combine influence of these factors significantly alters the features of electron acoustic waves in nonplanar geometry. This study is expected to contribute to the understanding of the nonlinear principles that underlie nonplanar electrostatic waves in laboratory plasmas as well as space.

Vlasov simulations of electric propulsion beam

Abstract A grid-based Vlasov simulation model is developed to simulate the two-dimensional unmagnetized electric propulsion (EP) plasma beam emission process. Comparing to the standard fully kinetic Particle-in-Cell simulation, the grid-based Vlasov simulation method eliminates the interference of particle noise and is capable of resolving higher-order velocity moment, such as electron heat flux, accurately. Vlasov simulations are carried out to investigate the effects of microscopic electron kinetics on macroscopic electron thermodynamics in EP beam. We find that the electron velocity distribution function (eVDF) exhibits a near-Maxwellian shape but with a depleted negative velocity tail in the beam direction and a ‘top-hat’ shape in the transverse direction. Macroscopically, the electrons confined within the quasi-neutral beam core region has a near constant temperature along the beam direction but follow a near-adiabatic cooling process as they expand outward in the transverse direction. The electron heat flux is dominated by the x-direction tensor component. The connection between the eVDF skewness and the electron heat flux suggests a pathway to develop a microscopic physics based electron closure relation for macroscopic electron thermodynamic process in unmagnetized plasma beam expansion.

Relativistic and Heavy Ion Effects on Single‐ and Multi‐Soliton Structures of Ion‐Acoustic Waves

ABSTRACTThe fundamental characteristics of ion‐acoustic waves (IAWs) due to the relativistic effects are investigated in a collisionless unmagnetized plasma system consisting of relativistic positively charged inertial heavy ions, kappa‐distributed electrons, and Maxwellian light ions. The reductive perturbation method (RPM) is used to derive the nonlinear evolution equation like the Korteweg‐de Vries (KdV) equation. The production of single‐, double‐, and triple‐IAW solitons (IAWSs) is also investigated. It is found that for the effects of concerned parameters only rarefactive (IAWSs) are produced. The results obtained in this study are useful not only to understand the space plasma phenomena such as plasma sheet boundary layer of earth's magnetosphere, laser‐plasma interaction, but also to validate the laboratory experiments.

Manifestations of inertia on light dragging revealed in plasmas

Light dragging phenomena in accelerated media have classically been modelled neglecting the effect of inertia on the dielectric response of the media. Here, we show that the inertial corrections due to a rotating motion can have a profound impact on light-dragging manifestations, leading notably to birefringence in media that are isotropic at rest. By applying these findings to a rotating unmagnetized plasma, we further reveal how inertia plays, in this case, a dominant role, offering unique opportunities to expose these new effects. Inertia is notably demonstrated to be the source of non-zero drag and enhanced polarization drag, pointing to fundamental differences between linear and angular momentum coupling. In taking advantage of the singular properties of plasmas, this work more generally underlines how rest-frame properties are affected by an accelerated motion, and how these modifications can carry over to wave dynamics.

Bifurcation analysis of Van der Pol–Mathieu equation for the dust grain charge with regularized (κ)-distributed electron-ion

This paper presents a novel viewpoint on nonlinear dust-acoustic waves (DAWs) in an unmagnetized collisionless plasma containing regularized [Formula: see text] distributed electrons and ions (ei) and negative dust grain. The nonlinear oscillatory system based on hybridization of the Van der Pol–Mathieu equation (VdPME) is derived by a new technique. By bifurcation analysis of the planar dynamical system (DS), the effects of parameters with the assistance of phase planes and time series of VdPME are studied. After analyzing the equation to identify the resonance region, a fourth-order Runge–Kutta method is used to solve it numerically. We explained the behavior of DA periodic, stable limit cycle, and chaotic limit cycle wave solutions with different parameters. These types of numerical solutions are illustrated in two-dimensional and three-dimensional graphics by changing the rate at which charged dust grain is produced [Formula: see text], as well as waste [Formula: see text] and comparing the results with those of earlier research. A novel bifurcation analysis of VdPE and VdPME is obtained with the effects of the cut-off factor [Formula: see text] of regularized [Formula: see text]-distribution (RKD) distributed ei, the superthermality of ei particles [Formula: see text], the ratio of ion to electron temperature [Formula: see text], and the ratio of dust to electron density [Formula: see text] illustrated. It is noticed that the DAW shows promotion in width and amplitude as the frequency [Formula: see text] increases and it becomes rarefaction as the cut-off parameter [Formula: see text] increases. On the contrary, it becomes compressive under the impact of superthermality [Formula: see text] and [Formula: see text]. The obtained conclusions may help explain and comprehend a variety of applications in experimental plasma containing highly energy regularized [Formula: see text] dispersed ei, as well as in the interstellar medium.

Electromagnetic Surface Waves in a Relativistic Magnetized Plasma Propagating in a Cylindrical Column

Dispersion relations of electromagnetic surface waves in a magnetized relativistic plasma propagating in a cylindrical column surrounded by vacuum are derived by means of the relativistic fluid equations. The zero order relativistic beam is assumed to stream along the direction of the axial magnetic field. The coupled equations of the E- and B-wave modes are solved analytically in terms of the cylindrical coordinates in weak or intermediate values of the magnetic field in which the cyclotron frequency is much smaller than the relativistic Doppler-shifted frequency. The entangled field components of the E- and B-waves are decoupled by assuming that the flow is incompressible. The surface wave dispersion relations of the E- and B-wave modes show a strong similarity and symmetry. The static magnetic field splits the E- and B-waves, thus doubling the modes in unmagnetized plasma. By taking the radius of the cylinder infinite, the dispersion relations in a semi-infinite plasma are derived.

Wakefield-driven filamentation of warm beams in plasma.

Charged and quasineutral beams propagating through an unmagnetized plasma are subject to numerous collisionless instabilities on the small scale of the plasma skin depth. The electrostatic two-stream instability, driven by longitudinal and transverse wakefields, dominates for dilute beams. This leads to modulation of the beam along the propagation direction and, for wide beams, transverse filamentation. A three-dimensional spatiotemporal two-stream theory for warm beams with a finite extent is developed. Unlike the cold beam limit, diffusion due to a finite emittance gives rise to a dominant wave number and a cutoff wave number above which filamentation is suppressed. Particle-in-cell simulations with quasineutral electron-positron beams in the relativistic regime give excellent agreement with the theoretical model. This paper provides deeper insights into the effect of diffusion on filamentation of finite beams, crucial for comprehending plasma-based accelerators in laboratory and cosmic settings.

Exploring Nonlinear Fractional (2+1)-Dimensional KP–Burgers Model: Derivation and Ion Acoustic Solitary Wave Solution

The purpose of this study is to conduct a complete examination into the fractional (2+1)-dimensional nonlinear KP-Burgers (KP-B) model in the setting of quantum plasma. The main goal is to present a mathematical explanation and derivation for the fractional (2+1)-dimensional nonlinear KP-B model. We used the reductive perturbation technique to obtain the fractional (2+1)-dimensional ion acoustic solitary wave, which leads to the nonlinear KP-B model. To solve the fractional space-time KP-B model, we used the modified sub-equation technique and the extended hyperbolic function methodology. This methodology covers rational, periodic wave, and hyperbolic function solutions. Ion acoustic waves were explored in relation to the effects of ion pressure and an external electric field. The effects of density and fractional order on the properties of a single solution are examined. The plasma system is defined as an unmagnetized epi plasma system composed of relativistic ions, positrons, and nonextensive electrons that can be found in a range of astrophysical and cosmological environments. The solution variables include electron-positron and ion-electron temperature ratios, electron and positron nonextensivity strength, ion kinematic viscosity, positron concentration, and the weakly relativistic streaming factor. The fractional order and associated plasma properties have a considerable influence on the phase velocity of ion acoustic waves. When the fractional order equals one, the obtained results are consistent with known outcomes. This work makes a substantial contribution to our understanding of nonlinear events in quantum plasmas, particularly ion acoustic waves. It provides a solid approach for solution development and analysis, with implications for a variety of astrophysical and cosmological scenarios.

Soliton interaction in a two-temperature electron plasma with trapping and superthermality effects

Head-on collision of the two small-amplitude electron-acoustic (EA) solitons is studied in an unmagnetized collisionless plasma in the presence of superthermal (hot) trapped electrons. For this purpose, using a well-known extended Poincare–Lighthill–Kuo (PLK) method, a pair of the trapped Korteweg–de Vries (tKdV) equations is derived to investigate the soliton trajectories and phase shifts. The latter are found dependent on amplitudes of the interacting solitons, effectively altering with hot-electron superthermality and plasma parameters. Typical parameters for the electron diffusion region (EDR) and day-side auroral zone have been selected to examine the impact of hot-electron superthermality, trapping parameter, hot-to-cold electron number density ratio, and cold-to-hot electron temperature ratio on the profiles of potential excitations and phase shifts of interacting solitons. It is found that phase speed of the EA waves becomes altered by varying the κ–parameter, strongly modifying the nonlinearity and dispersive coefficients in a superthermal trapped plasma. However, particle trapping phenomenon does not affect the linear phase speed but introduces a fractional nonlinearity in the tKdV equations of two interacting solitons. The impact of the adiabatic and isothermal pressures is also highlighted to show new modifications in the propagation characteristics of two interacting solitons.

THz radiation generation in the unmagnetized plasma due to beating of two Hermite Cosh Gaussian lasers in the presence of frequency chirp

THz radiation generation in the unmagnetized plasma due to beating of two Hermite Cosh Gaussian lasers in the presence of frequency chirp