Magnetized Plasma System Research Articles

Obliquely Propagating Self-Gravitational Shock Waves in Non-Relativistic Degenerate Quantum Plasmas

A rigorous theoretical investigation has been carried out on the propagation of non-linear self-gravitational shock waves (SGSHWs) in a magnetized super dense degenerate quantum plasma system (DQPS) composed of inertia-less non-relativistic degenerate electrons and inertial non-degenerate extremely heavy nuclei/element. The nonlinear propagation of these SGSHWs in the plasma system under consideration is studied by the standard reductive perturbation technique, which is valid for a small finite amplitude limit. The nonlinear dynamics of the SGSHWs are found to be governed by the Burgers equation. The Burgers equation is derived analytically and solved numerically. It has been found that the considered plasma model supports positive potential shock waves only. The fundamental properties (amplitude, steepness, etc.) of these SGSHWs are significantly modified by the variation of kinematic viscosity, obliqueness and number density of the plasma species. The results of our present investigation can be applied to astrophysical compact objects like neutron stars. Journal of Engineering Science 15(1), 2024, 21-29

Kinetic Alfvén solitary waves in astrophysical plasmas

The magnetospheric plasma (hot and thin) and the solar wind plasma (cold and dense) are separated by the Earth’s magnetopause, in which plasmas of both origins coexist. Different types of plasma diffusions are found due to this plasma mixing, and kinetic Alfvén solitary waves (KASWs) are one of them. In this work, a theoretical approach is taken to study the fundamental properties of heavy ion acoustic KASWs (HIAKASWs) in a magnetized plasma system whose constituents are nonextensive q-distributed two temperature electrons with dynamical heavy ions. The perturbations of the magnetized collisionless plasma system are investigated using the reductive perturbation technique to deduce the Korteweg–de Vries (K–DV) and modified K–DV (MK–DV) equations to determine the fundamental characteristics of small, but finite amplitude HIAKASWs. The presence of nonextensive electrons, magnetic field, obliquity angle (the angle between the external magnetic field and wave propagation), plasma particle number densities, and the temperature of various plasma species are observed to significantly alter the fundamental properties of HIAKASWs. The findings of our present study may be useful for comprehending the nonlinear wave properties in diverse interstellar plasma environments.

Laser Measurement of Anomalous Electron Diffusion in a Crossed-Field Plasma.

The anomalous diffusion of particles and energy in magnetized plasma systems is a widespread phenomenon that can adversely impact their operation and preclude predictive models. In this Letter, this diffusion is characterized noninvasively in a low-temperature, Hall-type plasma. Laser-induced fluorescence and incoherent Thomson scattering measurements are combined with a 1D generalized Ohm's law to infer the time-averaged inverse Hall parameter, a transport coefficient that governs cross-field diffusion. While the measured diffusion profile agrees with model-based estimates in magnitude, the measurements do not exhibit the steep "transport barrier" typically imposed in models. Instead, these results show that the electric field is primarily driven by a diamagnetic contribution due to the large peak electron temperature exceeding 75eV. This finding motivates a reconsideration of nonclassical energy transport across field lines in low-temperature plasmas.

The Evolution of Photospheric Magnetic Fields at the Footpoints of Reconnected Structures in the Solar Atmosphere

Magnetic reconnection is believed to play an important role in the release and conversion of energy among magnetized plasma systems. So far, we have been unable to understand under what conditions magnetic reconnection can take place. Based on observations from the New Vacuum Solar Telescope and the Solar Dynamics Observatory (SDO), we study 16 magnetic reconnection events, and each event has a clear X-type configuration consisting of two sets of atmospheric structures. We focus on 38 footpoints that are relevant to these structures and can be clearly determined. By using SDO/Helioseismic and Magnetic Imager line-of-sight magnetograms, we track the field evolution of these footpoints. Prior to the occurrence of magnetic reconnection, the associated fields at the footpoints underwent convergence and shear motions, and thus became enhanced and complex. During the converging period, the rates of increase of the mean magnetic flux densities (MFDs) at these footpoints are 0.03–0.25 hr−1. While the unsigned mean MFDs are 70–300 G, magnetic reconnection in the solar atmosphere takes place. Subsequently, the photospheric fields of these footpoints diffuse and weaken, with rates of decrease of the MFDs from 0.03 to 0.18 hr−1. These results suggest that, due to the photospheric dynamical evolution at the footpoints, the footpoint MFDs increase from a small value to a large one, and the corresponding atmospheric magnetic fields become complicated and nonpotential; then reconnection happens and it releases the accumulated magnetic field energy. Our study supports the conjecture that magnetic reconnection releases free magnetic energy stored in the nonpotential fields.

ALLIANCE: Spectral solver for kinetic plasma turbulence

The ALLIANCE (ALLIANCE - spectrAL soLver for kInetic plAsma turbuleNCE) code is developed to solve a new set of four-dimensional electromagnetic drift-kinetic equations in slab geometry [1]. The nonlinear equations are useful for the study of magnetized plasma systems at scales comparable to, or larger than the ion gyroradius. In particular, it is suited for the study the kinetic turbulent cascade in astrophysical plasma, while preserving finite Larmor radius effects at the fluid-kinetic transition. The equations solved are in spectral Fourier-Laguerre-Hermite form, a pseudo-spectral approach is used for the nonlinear terms, and the code is parallelised over multiple directions. After a presentation of the code, validation runs are shown, and benchmarks for serial and parallel computations are presented.

Arbitrary amplitude electron acoustic solitary excitations with Cairns–Tsallis distributed hot electrons and positrons in magnetized space plasmas

A rigorous theoretical study is performed to understand the characteristics of nonlinear electron acoustic (EA) solitary waves propagating in collisionless magnetized plasma system comprising cold inertial electrons, nonthermal–nonextensive hot electrons and positrons and stationary ions. The propagation and evolution of two potential modes (fast and slow) are studied in the linear regime. By employing magnetic hydrodynamic equations and with the aid of travelling wave approximation, the nonlinear wave dynamics is demonstrated by the first integral of motion in the form of a pseudo-energy balance equation. In exploring the EA soliton characteristics, numerical results reveal that only negative polarity EA solitons exist in a restricted range of the physical parametric space of the plasma system. It is revealed that the effects of nonthermal and nonextensive parameters, hot to cold electron density ratio, Mach number and magnetic strength considerably modify the basic properties of solitary waves. The present results may be important in space plasmas as well as laboratory plasmas with non-Maxwellian particle population.

The higher-order nonlinearity and parametric effects on dust-ion-acoustic shock waves

In the case of obliquely propagated small-amplitude shock waves, in this study, we investigate the impacts of higher-order nonlinearity as well as various parameters (such as dust concentrations, viscosity, trapping parameters, etc) on the shock wave structures. The considered magnetized plasma system consists of three components, such as inertial positive ions (mobile), trapped electrons, and immobile negatively charged dust particles. The modified Burgers equation with a dominating dissipative term (in which the viscous effect is significant) is derived initially to examine the lower-order nonlinear and dissipative effects, and then, to the best of our knowledge, the modified Burgers-type linear inhomogeneous equation is derived for the first time to observe the higher-order nonlinear effects on shock waves while the plasma contains trapped electrons. The reductive perturbation method is used for the derivation of the equations, whereas the Abel’s theorem and the method of variation of parameters are used for adding the higher-order effect. From the theoretical investigation, we observe that the higher-order nonlinearity has an increasing effect on the shock amplitude. Furthermore, the viscosity and dust concentration increase the shock width and the phase speed, respectively.

Chern invariants of topological continua: A self-consistent nonlocal hydrodynamic model

Topological systems are characterized by integer Chern invariants. In a continuous photonic system characterized by a local Drude model, the material response is ill-behaved at large wavenumbers, leading to noninteger Chern invariants and ambiguity in the existence of topological edge modes. This problem has been solved previously by introducing an ad hoc material model including a spatial cutoff material response, which leads to a finite Brillouin zone and integer invariants. In this work, we calculate Chern numbers in magnetized continuous plasma systems by considering the effect of nonlocality using a hydrodynamic (HD) Drude model. Then we argue that this model presents several advantages compared with the previous models, e.g., introducing physical response at large wavenumbers and integer Chern invariants with sum to zero without the need for an interpolated material response. Therefore the HD model forms a complete and self-consistent model, which resolves the Chern number issues in topological photonic continua.

Nonlinear excitations and dynamic features of dust ion-acoustic waves in a magnetized electron–positron–ion plasma

Abstract A wide class of nonlinear excitations and the dynamics of wave groups of finite amplitude ion-acoustic waves are investigated in multicomponent magnetized plasma system comprising warm ions, and superthermal electrons as well as positrons in presence of negatively charged impurities or dust particles. Employing the reductive perturbation technique (RPT), the Korteweg–de-Vries (KdV) equation, and extended KdV equation are derived. The presence of excess superthermal electrons as well as positrons and other plasma parameters are shown to influence the characteristics of both compressive and rarefactive solitons as well as double layers (DLs). Also, we extend our investigation by deriving the nonlinear Schrödinger equation from the extended KdV equation employing a suitable transformation to study the wave group dynamics for long waves. The analytical and numerical simulation results demonstrate that nonlinear wave predicts solitons, “table-top” solitons, DLs, bipolar structure, rogue waves, and breather structures. Moreover, implementing the concept of dynamical systems, phase portraits of nonlinear periodic, homoclinic trajectories, and supernonlinear periodic trajectories are presented through numerical simulation.

Three-dimensional modulational instability of dust acoustic waves in the presence of generalized (r, q) distributed electrons

A three-dimensional (3D) modulational instability (MI) of dust acoustic waves (DAWs) in a three-component magnetized dusty plasma system consisting of a negatively charged fluid, inertialess generalized (r, q) distributed electrons and Boltzmann distributed ions, is investigated. The basic system of the nonlinear hydrodynamic equations is reduced to a 3D nonlinear Schrödinger equation (NLS) which is valid for small but finite amplitude DAWs using a reductive perturbation technique. The domain of the stability and instability regions is investigated that is strongly affected by the spectral parameters of the generalized (r, q) distribution and the electron-to-ion temperature ratio (T e /T i ). The existence domains for observing the first-and second-order solutions of the dust acoustic rogue waves (DARWs) are determined and the basic features (viz the width and amplitude) for the first-order solution are found to be significantly dependent on the system physical parameters changes such as T e /T i , number density ratio [n e0/(n d0 z d0)] and the dust cyclotron frequency (ω cd ) as well as the spectral indexes r and q. A comparison between the first-and second-order DARW amplitudes is presented. Moreover, another comparison between the first-order DARW amplitudes obtained by generalized (r, q) distributed electrons and those corresponds to Maxwellian is provided. Finally, implication of our consequences in specific plasma situations are briefly discussed.

Shock waves in magnetized plasmas with superthermal trapped electrons.

Formation of ion-acoustic shock waves (IAShWs) and their propagation nature in a magnetized plasma in the presence of superthermal trapped electrons are investigated for the first time via the fluid dynamical approach. A magnetized plasma system, comprising of inertial ions and non-inertial electrons following κ-superthermal trapped distribution, is considered to examine the basic features (amplitude, width, phase speed, etc.) of IAShWs in such a plasma. A diffusion effect (due to the ion kinematic viscosity) is taken into account. The reductive perturbation technique is adopted to derive the modified Korteweg de-Vries Burgers’ (mKdVB) equation and the solution of mKdVB equation (derived by adopting the tangent hyperbolic method) is used to investigate the dynamical and structural characteristics (speed, amplitude, width, etc.) of IAShWs. The influence of relevant plasma (configuration) parameters (e.g., the superthermality index κ, concentration of trapped electrons, external magnetic field, and obliquity angle, etc.) on the nature of IAShWs is examined. The applications of the results in space and laboratory plasma environments, where nonthermal trapped electrons are available, are briefly discussed.

Influence of quantum correction on the Jeans instability of strongly coupled magnetized plasma

It is shown that the Jeans instability condition of strongly coupled finitely conducting gaseous plasma is reduced in the presence of magnetic field and quantum correction. The linearized equations are constructed by using the Quantum magneto-hydrodynamic (QMHD) model. With the help of the normal mode analysis method, a general dispersion relation is obtained. This dispersion relation is discussed by a different mode of propagation. In this paper, it has been found that, quantum correction stabilizes the growth rate of the organization but the relaxation time and electrical resistivity destabilize the growth rate in the transverse mode of propagation. Further, the modified Jeans criterion of the instability of the magnetized plasma system has been also found.

Dust-acoustic Gardner solitons in cryogenic plasma with the effect of polarization in the presence of a quantizing magnetic field

Abstract A theoretical investigation is presented for dust-acoustic (DA), Gardner solitons (GSs), and double layers (DLs) in a magnetized cryogenic plasma system. The plasma consists of inertial negatively charged dust, Boltzmann distributed electrons, and ions, all existing in a quantizing magnetic field. The Korteweg–de Vries (KdV), a modified KdV (mKdV), and Gardner equations are derived by using the reductive perturbation method. It is found that the KdV solitons and DLs are either compressive or rarefactive depending on the plasma parameters, whereas only compressive mKdV and rarefactive GSs solitons exist. These GSs and DLs are significantly modified due to the introduction of the polarization force effect. The present results are considered to be beneficial in understanding the waves propagating at cryogenic temperatures in the experiments of the nano-electromechanical application such as cryogenic etching of silicon that leads to etched silicon and makes it highly anisotropic with a high etch rate, lower side etching, and increases the dry etch resistance of organic masks.

Photon polarization tensor in a magnetized plasma system

We investigate the photon polarization tensor at finite temperatures in the presence of a static and homogeneous external magnetic field. In our scheme, the summing of the Matsubara frequency is performed after Poisson resummation, which is easily completed and converges quickly. Moreover, the behaviors of finite Landau levels are presented explicitly. It shows a convergence while summing infinite Landau levels. Consequently, there is no necessity to truncate the Landau level in a numerical estimation. At zero temperature, the lowest Landau level (LLL) approximation is analytically satisfied for the vacuum photon polarization tensor. However, we examine that the LLL approximation is not enough for the thermal polarization tensor. The thermal tensor obtains non-trivial contributions from the finite-n Landau levels. And, photon spectra gains a large imaginary contribution in thermal medium, which is the so-called Landau damping. Finally, it is argued that the summation of Matsubara frequency is not commuted with Landau level ones, such conjecture is excluded in our calculations.

Dynamics of ion-acoustic waves in nonrelativistic magnetized multi-ion quantum plasma: the role of trapped electrons

The presented work provides a new perspective of quantum nonlinear propagation of ion-acoustic (IA) waves in a magnetized collisionless and dissipative multi-ion plasma system, composed of cold positive and negative charged nonrelativistic ions, negatively charged immobile heavy ions and trapped electrons; all existed in a quantizing magnetic field. We address the reductive perturbation method to derive the Korteweg-de Vries- Burgers (KdV-Burgers) and modified KdV-Burgers equations. The bifurcation theory of planar dynamical systems is applied to investigate the existence of the solitary wave and the periodic traveling wave solutions of the resulting mKdV-Burgers equation. Accordingly, the phase portrait topology is illustrated for this equation. To study the nonlinear waves in case of mKdV- Burgers, we obtain some interesting physical solutions for mKdV- Burgers. These solutions are in the form of soliton, a combination between the shock and the soliton, and finally monotonic and oscillatory shock waves. Only rarefactive IA waves are obtained for the slow mode of phase velocity. It is found that the IA solitons, IA shocks are affected by the plasma system parameters. The presented theoretical research can be successfully implemented to understanding the solitary and shocks structures in dense magnetized quantum plasmas such as those existing in white dwarfs and in the intense-laser plasma interactions.

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.

Radiative and gravitating modes in the partially ionized magnetized dusty plasma

In the present study, fluid theory is used to investigate the gravitational and radiative condensation instabilities of a partially ionized magnetized dusty plasma system. The effects of ion and electron capture by dust grains, the charge variation of dust grains, and the radiative effects of electron species are also taken into account. The dynamics of all four species are considered to derive modified densities that further lead to a general dispersion relation. The general dispersion relation describes the propagation of low frequency electrostatic dust acoustic waves in magnetized self-gravitating partially ionized dusty plasma with ionization-recombination, dust charge variations, and radiative effects. Gravitational modes of propagation and radiative modes of propagation are illustrated separately for both parallel and perpendicular cases. Conditions for instabilities are also derived to explain the gravitational collapse and radiative condensation of the system. The numerical results are presented to signify the role of dust neutral collision frequency, dust charge fluctuation, magnetic field, and recombination ionization effects on both the radiative condensation and gravitational instabilities. The relevance of the present study to interstellar molecular clouds is also discussed and the effect of considered parameters on the critical wavelength, critical wave number, luminosity, etc., has been investigated.

Drift wave in strong collisional dusty magnetoplasma

The study about the wave mechanism of magnetized dusty plasmas has important value to related experiment, industrial processing and exploring celestial space. The linear and nonlinear fluctuation characteristics of the nonuniform magnetized dust plasma system are researched in this paper. For the homogeneous external magnetic field and the nonuniform environment with density and temperature gradients, a two-dimensional nonlinear dynamic magnetoplasma equation is derived considering the strong impact between dust and neutral particles. The linear dispersion relation is obtained by the linearized method. There are both the damping wave causing by strong collision and the harmonic wave by particle drift. Employing the typical numerical parameters for analysis, the results display that the quantum parameter modifies the system lengths; the real wave frequency is proportion to the drift frequency; the imaginary wave frequency has complex relationship with the collision frequency between dust and neutrals, and the collision of particles causes the dissipation effects to the system. Besides, the analytical solutions of drift shock wave and explosive wave are solved by function change method. The variation about the electrostatic potential with the main physical parameters is discussed in detail. It is shown that the strength of the electrostatic shock wave and the width of the explosive wave increase with increasing the dust density and magnetic field intensity, decrease with increasing the collision frequency, change with the drift velocity. When the space-time phase is small, the electrostatic potential changes quickly; once big enough, the potential tends to be stable value and reaches stable state eventually. Finally, the stability of the system is discussed. It is found that the dusty charge, quantum parameter, drift velocity all appear in the disturbed solution. All these results in the paper show that the strong collision effect, quantum effect, particle drift and magnetic field all play important role to the generation, evolution and stability of drift waves.

Electroacoustic Waves in a Collision-Free Magnetized Superthermal Bi-Ion Plasma

The electroacoustic waves, particularly ion-acoustic waves (IAWs), and their expansion in the medium of a magnetized collision-free plasma system has been investigated theoretically. The plasma system is assumed to be composed of both positively and negatively charged mobile ion species and kappa-distributed hot electron species. In the nonlinear perturbation regime, the magnetized Korteweg–de Vries (KdV) and magnetized modified KdV (mKdV) equations are derived by using reductive perturbation method. The prime features (i.e., amplitude, phase speed, width, etc.) of the IAWs are studied precisely by analyzing the stationary solitary wave solutions of the magnetized KdV and magnetized mKdV equations, respectively. It occurs that the basic properties of the IAWs are significantly modified in the presence of the excess superthermal hot electrons, obliqueness, the plasma particle number densities, etc. It is also observed that, in case of magnetized KdV solitary waves, both compressive and rarefactive structures are formed, whereas only compressive structures are found for the magnetized mKdV solitary waves. The implication of our results in some space and laboratory plasma situations is concisely discussed.

Dust-ion-acoustic solitary waves in magnetized plasmas with positive and negative ions: The role of electrons superthermality

The formation of dust-ion-acoustic solitary waves (DIASWs), and their basic properties in a magnetized dusty plasma system containing inertial, hot positively and negatively charged ion fluids, κ-distributed superthermal electrons, and negatively charged stationary dust species are investigated theoretically. An ambient magnetic field is assumed along z-direction, and the wave propagation is considered obliquely to the direction of that ambient magnetic field. Two types of modes, the fast and the slow modes, are shown to exist in the linear regime. The reductive perturbation method (which is valid for small but finite amplitude DIASWs) as well as pseudo-potential approach (which is valid for arbitrary amplitude DIASWs) are employed to identify the basic properties of the DIASWs. The effects of key plasma composition parameters, namely the superthermality effect of electrons, the temperature of positive and negative ions, the number density of positive and negative ions, on the dynamics of small amplitude as well as on large amplitude DIASWs, are investigated. The influence of the obliquity parameter and the magnetic field on the propagation characteristics of DIASWs are also examined.