Anisotropic Magnetized Plasma Research Articles

Unconditionally Stable Crank-Nicolson Algorithm with Enhanced Absorption for Rotationally Symmetric Multi-Scale Problems in Anisotropic Magnetized Plasma

Unconditionally Stable Crank-Nicolson Algorithm with Enhanced Absorption for Rotationally Symmetric Multi-Scale Problems in Anisotropic Magnetized Plasma

Theory of a Square Loop Antenna in an Anisotropic Magnetized Plasma

Theory of a Square Loop Antenna in an Anisotropic Magnetized Plasma

Three-dimensional rogue waves and dust-acoustic dark soliton collisions in degenerate ultradense magnetoplasma in the presence of dust pressure anisotropy

A three-dimensional Thomas–Fermi dense anisotropic magnetized plasma having Fermi–Dirac distributed ions and electrons as well as classical fluid negative dust impurities is considered to analyze oblique modulational instability (MI) and head-on collisions among dust-acoustic dark solitons. The Chew–Golberger–Low description is employed to define the anisotropic dust pressure. The linear analysis is investigated. It is found that for larger wavelengths, the pressure anisotropy has a strong effect on the wave frequency. Following the multiscale reductive perturbation technique, a (3 + 1)-dimensional nonlinear Schrödinger equation is derived. Also, the MI criterion is identified, and the regions of (un)stable modulated waves are determined precisely. In addition to that, (un)stable domains of the modulated structures as well as the profile of the dust-acoustic rogue waves are found to be strongly affected by dust grain density, pressure anisotropy, and the strength of the magnetic field. In the stable regions, the face-to-face dark soliton collision and their phase shifts as well as their analytical trajectories are reported by applying the extended Poincare–Lighthill–Kuo method. Numerical analysis reveals that the phase shifts increase with dust concentration but decrease with dust pressure anisotropy. The present results may be applicable in exploring the nonlinear wave dynamics and solitary wave interactions in dense astrophysical plasmas especially to white dwarfs, interiors of the neutron stars, and magnet stars.

Transmission characteristics of terahertz Bessel vortex beams through a multi-layered anisotropic magnetized plasma slab

The transmission of terahertz (THz) Bessel vortex beams through a multi-layered anisotropic magnetized plasma slab is investigated by using a hybrid method of cylindrical vector wave functions (CVWFs) and Fourier transform. On the basis of the electromagnetic boundary conditions on each interface, a cascade form of expansion coefficients of the reflected and transmitted fields is obtained. Taking a double Gaussian distribution of the plasma density as an example, the influences of the applied magnetic field, the incident angle and polarization mode of the incident beams on the magnitude, OAM mode and polarization of the transmitted beams are analyzed in detail. The results indicate that the applied magnetic field has a major effect upon the polarization state of the transmitted fields but not upon the transmitted OAM spectrum. The incident angle has a powerful influence upon both the amplitude profile and the OAM spectrum of the transmitted beam. Furthermore, for multiple coaxial vortex beams, an increase of the maximum value of the plasma density causes more remarkable distortion of both the profile and OAM spectrum of the transmitted beam. This research makes a stable foundation for the THz OAM multiplexing/demultiplexing technology in a magnetized plasma environment.

Modulation of multi-dimensional waves in anisotropic magnetized plasma

Modulation of multi-dimensional waves in anisotropic magnetized plasma

Hybrid Implicit-Explicit Procedure With Improved Absorption for Anisotropic Magnetized Plasma in Bandpass Problem

Although several algorithms have been developed for the simulation of anisotropic magnetized plasma, they still show decrement of efficiency especially with fine structures along a single direction. By incorporating the complex envelope method, higher order concept, one-step leapfrog hybrid implicit- explicit (HIE) procedure and perfectly matched layer (PML) formulation, such algorithm is proposed to take advantages of them in bandpass simulation of fine structures. In addition, in order to simulate the magnetized plasma with unique anisotropic property, auxiliary differential equation method is modified according to the proposed unconditionally stable scheme. From the aspect of both theoretically and numerically, corresponding numerical examples and experiment are carried out for the further demonstration of effectiveness. The results indicate that the proposed scheme which can break the Courant-Friedrichs-Levy (CFL) condition shows considerable entire performance in the bandpass anisotropic magnetized plasma simulation with fine structure along a single direction.

Perfectly Matched Layer for Accurate FDTD for Anisotropic Magnetized Plasma

In this work, we propose a stable perfectly matched layer (PML) for accurate finite-difference time-domain (FDTD) methods for analyzing electromagnetic wave propagation in the anisotropic magnetized plasma region. Toward this purpose, we apply the complex frequency-shifted PML systematically to the E-J collocated FDTD method. In specific, auxiliary PML variables are included in the matrix calculation involved in the final update equations of the E-J collocated FDTD method. Numerical examples are used to validate the proposed PML-FDTD for anisotropic magnetized plasma.

Performance Enhanced Crank-Nicolson Boundary Conditions for EM Problems

Based upon the approximate Crank–Nicolson (CN) algorithms and the higher order (HO) concept, unconditionally stable perfectly matched layer (PML) implementations are proposed for electromagnetic problems in the finite-difference time-domain (FDTD) lattice. The approximate CN algorithms include the CN direct-splitting (CNDS) and CN approximate-factorization-splitting (CNAFS). The proposed schemes take advantage of the approximate CN algorithms in terms of eliminating the Courant–Friedrichs–Levy stability condition and maintaining the computational accuracy. By introducing the HO concept to the PML formulation, the absorbing performance can be enhanced during the simulation. Furthermore, to cope with the existence of half-time-step problems in simulating the anisotropic magnetized plasma, a modified ADE method is proposed at the integer time step. Thus, the modified ADE method can be directly employed in the approximate CN algorithms. Numerical examples and experiments are carried out to demonstrate the effectiveness, efficiency, and performance. Through the results, it can be observed that the computational efficiency and absorbing performance can be significantly improved. Meanwhile, it can be concluded that the CNAFS-PML and CNDS-PML algorithms show higher accuracy and considerable efficiency, respectively, when the time step surpasses far beyond the CFL condition.

Jet quenching parameters in strongly coupled anisotropic plasmas in the presence of magnetic fields

I use the holographic gauge/gravity duality to systematically calculate the jet quenching parameters in strongly coupled anisotropic plasmas in the presence of external magnetic fields. The magnetic field breaks down spatial rotation symmetry from $SO(3)$ to $SO(2)$, leading to the presence of multiple anisotropic jet quenching parameters, which are evaluated here in two quite different holographic settings. One of them corresponds to a top-down deformation of the strongly coupled $\mathcal{N} = 4$ Super Yang-Mills plasma triggered by an external magnetic field, while the other one is a bottom-up Einstein-Maxwell-Dilaton model of phenomenological relevance for high energy peripheral heavy ion collisions, since it is able to provide a quantitative description of $(2+1)$-flavors lattice QCD thermodynamics with physical quark masses at zero and nonzero magnetic fields. I find for both models an overall enhancement of all the anisotropic jet quenching parameters with increasing magnetic fields. Moreover, I also conclude that for both models transverse momentum broadening is larger in transverse directions than in the direction of the magnetic field. Since these conclusions are shown to hold for two rather different holographic setups at finite temperature and magnetic fields, they are suggested as fairly robust features of strongly coupled anisotropic magnetized plasmas.

Unconditionally stable higher order perfectly matched layer applied to terminate anisotropic magnetized plasma

An effective and efficient absorbing boundary condition applied to terminate anisotropic magnetized plasma is proposed in this article. As its mathematical derivations are based on the high order perfectly matched layer (HO-PML) and Crank-Nicolson finite-difference time-domain method, it has the advantages of reducing late-time reflections, attenuating evanescent waves, absorbing low-frequency propagation waves and overcoming the Courant-Friedrichs-Levy condition. To validate the efficiency and effectiveness of the proposed HO-PML, a ridge waveguide model composed of vacuum and the anisotropic magnetized plasma, a dielectric waveguide model composed of the dielectric and the anisotropic magnetized plasma are employed. The numerical results show that the proposal can not only maintain the stability of the algorithm with the increment of the time step but also further enhance the absorbing performance.

Adjustable optical properties of extrinsic photonic crystals consisting of anisotropic magnetized plasma

Adjustable optical properties of a one-dimensional photonic crystal composed of isotropic dielectric layers and anisotropic magnetized plasma as a defect layer is theoretically investigated. By using the 4 × 4 transfer matrix method in the microwave region, the pronounced contrast in the positive and negative magnetic field for the both TE- and TM-polarized modes were demonstrated. The results indicate that the position frequency and the width of the optical filter can be made tunable by the application of an external magnetic field. Therefore, frequency position of the optical filter can either be red or blue shifted depending on the orientation of external magnetic field, also the width of the optical filter compresses at TE (TM) polarization at positive (negative) external magnetic fields. In additional, the role played with the incident angle on the filter properties for both transverse electric (TE) and transverse magnetic (TM) modes in the presence of the magnetic field is investigated. We hope this study may be taken into attention for the improvement in new perspectives in the design of new magneto-optic devices.

Unconditionally stable five‐step LOD‐FDTD method in plasma medium

AbstractA three‐dimensional unconditionally stable five‐step locally one‐dimensional finite‐difference time‐domain (LOD‐FDTD) method for anisotropic magnetized plasma medium is presented. Firstly, we search for a diagonal matrix to transform Maxwell coefficient matrix of plasma into skew symmetric matrix which is beneficial to analyze the properties of the proposed algorithm. Then, the detailed formula derivation and numerical stability analysis is presented. At last, the resonance frequency of a microwave cavity partially filled with a plasma slab and the rotation angle of an infinite plasma slab are simulated to verify the accuracy and stability of the proposed method. The effectiveness of the proposed method is further demonstrated by comparing with the three‐step LOD‐FDTD method.

Efficient PML implementation based on the unconditionally stable CN-FDTD algorithm for anisotropic magnetized plasma

Based on the bilinear transform (BT) method and the Crank-Nicolson-approximate-decoupling (CNAD) algorithm, an efficient unconditionally stable implementation of the stretched coordinate perfectly matched layer (SC-PML) is proposed to truncate anisotropic magnetized plasma. The dispersive magnetized plasma can be calculated by the modified auxiliary differential equation (ADE) method. The proposed SC-PML formulations not only have the advantage of the conventional PML in terms of the absorbing performances but also take the advantage of unconditional stability of the original CN algorithm. In this paper, numerical examples are provided in the two-dimensional domain with anisotropic magnetized plasma to validate the effectiveness of the algorithm. The results show that the proposed SC-PML is an unconditionally stable scheme for the time step which surpasses the Courant–Friedrichs–Lewy (CFL) condition and it has considerable absorbing performance.

FDTD Analysis of Propagation and Absorption in Nonuniform Anisotropic Magnetized Plasma Slab

In this paper, a current density convolution finite-difference time-domain method is extended to study the electromagnetic wave propagation and absorption in inhomogeneous magnetized plasmas. First of all, we analyze the wave propagation in homogeneous magnetized plasmas for arbitrary magnetic inclination angle. Then, we studied three types of plasma absorption, including plasma resonance, electron cyclotron resonance, and upper hybrid resonance in homogeneous and inhomogeneous magnetized plasmas. This model is applied to simulate the heating mechanism during ionospheric modification experiments by high-power high-frequency radio waves. These results have important implications for the interpretation of physical mechanisms for the interaction of high power radio waves with magnetized ionospheric plasmas and design of future experiments.

Structure formation through self-gravitational instability in degenerate and non-degenerate anisotropic magnetized plasma

The self-gravitational instability is examined for non-degenerate and degenerate magnetized plasma. In the case of non-degenerate collisionless magnetized plasma the pressure is considered as anisotropic while in the case of degenerate situations it is taken as isotropic. The effect of finite Larmor radius correction of non-degenerate ions and viscous dissipation is taken into account in both the cases. Firstly in non-degenerate anisotropic plasma the conventional magnetohydrodynamic model is used to construct basic set of equations within the framework of modified Chew–Goldberger and Low theory. Secondly, in the case of degenerate isotropic plasma, which is considered to be composed of degenerate electrons and non-degenerate ions, the model equations are constructed using quantum magneto hydrodynamic model. The dynamics of degenerate particles are governed by Bohm and exchange potentials. The general dispersion relations are derived for both degenerate and non-degenerate situations separately using linearized perturbation equations. The results are discussed analytically and numerically for various modes of propagation. In case of non degenerate strongly magnetized plasma the effects of stress tensor anisotropy dominate over the influence of FLR effects while the FLR effects prevail in the weak magnetic field region. In case of isotropic degenerate plasma the implications of exchange parameter on the Jeans mass have been estimated and it is found that the increase in exchange parameter increases the limit of Jeans mass. The Jeans length and Jeans mass have been estimated for the white dwarf stars as $L_{J} \approx 2.1 \times 10^{11}~\mbox{m}$ and $M_{J} \approx 5 \times 10^{39}~\mbox{kg}$ respectively assist the existence of super Chandrasekhar white dwarfs.

Unconditionally Stable LOD-FDTD Method in Anisotropic Magnetized Plasma

A three-step unconditionally stable locally 1-D approach is proposed, representing a dispersive anisotropic magnetized plasma medium. The accuracy and stability of the method are verified through simulation of wave propagation in a microwave cavity partially filled with a plasma slab. Finally, Faraday rotation across a plasma slab is simulated by the proposed method.

Stability Analysis of Electromagnetic Ordinary and Extraordinary Modes

By using kinetic theory, we derived the general dispersion relations for ordinary mode (O-mode) and Extra-ordinary mode (X-mode) in anisotropic magnetized plasma. The effects of energy anisotropy, magnetic field to density ratio () and the plasma beta on the propagation characteristics, have been analyzed. The stability analysis and the growth rates have been presented. The marginal threshold condition for oscillatory and purely growing mode has been obtained for higher harmonics and we have also calculated their growth rates in terms of plasma beta and energy anisotropy . The X-mode satisfies the instability condition according to difference of geometry with the O-Mode. These modes are important for spherical tokamaks, and their coupling leads to the generation of the Bernstein mode, which causes the heating effects.

Modeling of anisotropic magnetized plasma media using PLCDRC-TLM method

In this paper, the electromagnetic waves propagation in dispersive anisotropic magnetized plasma medium is modeled using transmission line matrix (TLM) method based on the piecewise linear current density recursive convolution (PLCDRC) formulation. The high efficiency and accuracy of the proposed formulation are confirmed by computing the reflection and transmission coefficients for a magnetized plasma layer. The schemes of PLCDRC-TLM and Runge-Kutta exponential time differencing (RKETD)-TLM algorithms are presented. A comparison of the numerical results of the PLCDRC-TLM and RKETD-TLM with analytical values in frequency-domain is included. Simulation results indicate that PLCDRC-TLM method is more accurate than RKETD-TLM algorithm.

A 3-D Stochastic FDTD Model of Electromagnetic Wave Propagation in Magnetized Ionosphere Plasma

A stochastic finite-difference time-domain (S-FDTD) algorithm is presented for electromagnetic-wave propagation in anisotropic magnetized plasma. This new algorithm efficiently calculates in a single simulation not only the mean electromagnetic field values, but also their variance as caused by the variability or uncertainty of the electron and ion content of the ionosphere. The structure of the ionosphere is often too variable and uncertain for electromagnetic-wave propagation problems to be solved using a deterministic formulation, particularly during space weather events. For these cases, the S-FDTD ionospheric plasma algorithm will serve as an important tool. For example, it could be used to determine the confidence level at which a communications or remote sensing or radar system will operate as expected under abnormal ionospheric conditions.

Caustic region fields of an elliptical reflector covered by an anisotropic magnetized plasma layer

Theoretical formulations of the electromagnetic (EM) field distribution in the focal or caustic region of an elliptical reflector with its curved surface coated by collisional magnetized anisotropic plasma have been derived. Both parallel and perpendicular polarizations of the normal incident wave are considered. Expressions for the EM field intensity along the focal region have been obtained accurately using Maslov’s method. The effect of the plasma-layer thickness on the reflected and transmitted field intensity distributions was investigated. Other physical parameters such as the plasma electron density, the cyclotron frequencies, and the collisional frequency have been noticed to have an evident influence on the levels of the transmitted field-intensities along the focal region. The problem discussed in this paper has, also, been solved using Kirchhoff’s approximation and the results of the two methods are found to be in a good agreement.