Wave Generation in a Warm Magnetized Multi‐Component Plasma

The resonant interaction between three waves propagating perpendicularly to an external magnetic field in a plasma is considered. We present the explicit expressions for the three wave coupling coefficients of a warm multi‐component plasma. The results of previous work on the generation of THz radiation by laser plasma interaction are significantly improved. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Magnetized Stiff Fluid Cylindrically Symmetric Universe with Two Degrees of Freedom in General Relativity

A magnetized stiff fluid cylindrically symmetric universe with two degrees of freedom for perfect fluid distribution, is investigated. The magnetic field is due to an electric current produced along x-axis. The distribution consists of an electrically neutral perfect fluid with an infinite electrical conductivity. The behaviour of the model in presence and absence of magnetic field is discussed. The other physical aspects of the model related to the observations are also discussed.     

Effects of Spin Quantum Force in Magnetized Quantum Plasma

Starting from the governing equations for a quantum magnetoplasma including the electron spin -1/2 effects and quantum Bohm potential, we derive Korteweg-de Vries (KdV) equation of the system of quantum magnetohydrodynamics (QMHD). The amplitude and width of magnetosonic soliton with different parameters in the system are studied. It is found that the normalized Zeeman energy E plays a crucial role, for E≥1 the amplitude r_mξ and the width w_ξ of solitary wave all decrease as E increases. That is, the introduction of spin quantum force modifies the shape of solitary magnetosonic waves and makes them more narrower and shallower.     

Relativistic Derivation of the Ponderomotive Force Produced by Two Intense Laser Fields

The ponderomotive force plays a fundamental role in the absorption of laser light on self-consistent plasma density profiles, in multiple-photon ionization, and in intense field electrodynamics. The relativistic corrections to the ponderomotive force of a transversely polarized electromagnetic wave lead to an approximately 20-percent reduction in the single particle ponderomotive force produced by a 10-?m 1016-W/cm2 laser field. Recent experimental investigations are based on using two intense laser fields to produce desired laser-matter interactions. This paper presents the first derivation of the nonlinear relativistic ponderomotive force produced by two intense laser fields. The results demonstrate that relativistic ponderomotive forces are not additive.     

Bianchi Type-III Magnetized Wet Dark Fluid Cosmological Model in General Relativity

Bianchi type-III cosmological model of universe filled with dark energy from a wet dark fluid (WDF) in presence and absence of magnetic field is investigated in general theory of relativity. We assume that F ₁₂ is the only non-vanishing component of F _ij . We obtain exact solutions to the field equations using the condition that expansion is proportional to the shear scalar i.e. (B=C ⁿ ). The physical behavior of the model is discussed with and without magnetic field. We conclude that universe model do not approach isotropy through the evolution of the universe.     

Self-Focusing of Quadruple Gaussian Laser Beam in an Inhomogenous Magnetized Plasma with Ponderomotive Non-Linearity:Effect of Linear Absorption

The propagation of quadruple Gaussian laser beam in a plasma characterized by axial inhomogeneity and nonlinearity due to ponderomotive force in the paraxial ray approximation is investigated.An appropriate expression for the nonlinear dielectric constant has been developed in the presence of external magnetic field,with linear absorption and due to saturation effects for arbitrary large intensity.The effects of different types of plasma axial inhomogeneities on self-focusing of laser beam have been studied with the typical laser and plasma parameters.Self-focusing of quadruple Gaussian laser beam in the presence of externally applied magnetic field and saturating parameter is found significantly improved in the case of extraordinary mode.Our results reveal that initially converging beam shows oscillatory convergence whereas initially diverging beam shows oscillatory divergence.The beam is more focussed at lower intensity in both cases viz.extraordinary and ordinary mode.     

Self-Focusing of Quadruple Gaussian Laser Beam in an Inhomogenous Magnetized Plasma with Ponderomotive Non-Linearity: Effect of Linear Absorption

The propagation of quadruple Gaussian laser beam in a plasma characterized by axial inhomogeneity and nonlinearity due to ponderomotive force in the paraxial ray approximation is investigated. An appropriate expression for the nonlinear dielectric constant has been developed in the presence of external magnetic field, with linear absorption and due to saturation effects for arbitrary large intensity. The effects of different types of plasma axial inhomogeneities on self-focusing of laser beam have been studied with the typical laser and plasma parameters. Self-focusing of quadruple Gaussian laser beam in the presence of externally applied magnetic field and saturating parameter is found significantly improved in the case of extraordinary mode. Our results reveal that initially converging beam shows oscillatory convergence whereas initially diverging beam shows oscillatory divergence. The beam is more focussed at lower intensity in both cases viz. extraordinary and ordinary mode.     

Bianchi Type I Magnetized Barotropic Perfect Fluid Cosmological Model in General Relativity

Bianchi Type I barotropic perfect fluid cosmological model in presence of magnetic field, is investigated. To get the deterministic model, we have also assumed that σ ₁¹ α θ where σ ₁¹ is the eigen-value of shear tensor σ _i ^j and θ the expansion in the model. The behavior of the model in presence and absence of magnetic field and singularities in the model are also discussed.     

Multi-ion Double Layers in a Magnetized Plasma

A theoretical investigation is carried out to study the existence, formation and basic properties of ion acoustic (IA) double layers (DLs) in a magnetized bi-ion plasma consisting of warm/cold ions and Boltzmann distributed electrons. Based on the reductive perturbation technique, an extended Korteweg de-Vries (KdV) equation is derived. The propagation of two possible modes (fast and slow), and their evolution are investigated. The effects of obliqueness, magnitude of the magnetic field, ion concentration, polarity of ions, and ion temperature on the IA DL profile are analyzed, and then the ranges of parameters for which the IA DLs exist are investigated in details.     

Ponderomotive Force Effects due to a Circularly Polarized Electromagnetic Wave

The modifications in the time-averaged plasma particle distribution functions in the presence of a large amplitude electromagnetic wave are studied. It is shown that the ponderomotive force is responsible for tail formation, non-zero particle currents and heat fluxes. Explicit results, which describe those effects, are derived.     

Multi-ion Double Layers in a Magnetized Plasma

A theoretical investigation is carried out to study the existence,formation and basic properties of ion acoustic(IA) double layers(DLs) in a magnetized bi-ion plasma consisting of warm/cold ions and Boltzmann distributed electrons.Based on the reductive perturbation technique,an extended Korteweg de-Vries(KdV) equation is derived.The propagation of two possible modes(fast and slow),and their evolution are investigated.The effects of obhqueness,magnitude of the magnetic field,ion concentration,polarity of ions,and ion temperature on the IA DL profile are analyzed,and then the ranges of parameters for which the IA DLs exist are investigated in details.     

Wave Propagation in a Magnetized Dusty Plasma

The properties of waves propagating in amagnetized dusty plasma are analyzed for both high andlow values of the ion-cyclotron frequency. The electronsare considered to be hot. The dispersion relation for a wave propagating through the dusty plasmaat an arbitrary angle with the external magnetic fieldis derived. This rectifies some errors in the earliertreatment of Cramer and Vladimirov (1996). Effects of the presence of the dust on thecharacteristics of wave propagation arediscussed.     

Bianchi .Type-I Massive String Magnetized Barotropic Perfect Fluid Cosmological Model in General Relativity

Bianchi type-I massive string cosmological model with magnetic field of barotropic perfect fluid distribution through the techniques used by Latelier and Stachel is investigated. To obtain the deterministic model of the universe, it is assumed that the universe is filled with barotropic perfect fluid distribution. The magnetic field is due to electric current produced Mong the x-axis with infinite electrical conduictivity. The behaviour of the model in the presence and absence of magnetic field together with other physical aspects is further discussed.     

Nonlinear Resonant Interaction of Two Longitudinal Waves and a Transverse Wave in a Hot Magnetized Plasma

By Whitham's method of averaged Lagrangian and using Low's form of Lagrangian, coupled mode equations and coupling coefficients are derived for resonant nonlinear interaction of two longitudinal and one transverse wave in a magnetized plasma, in which the later wave propagates along the external uniform magnetic field. The limiting form of these coupling coefficients are obtained when the external magnetic field vanishes.     

双向隐形传态方案及安全性分析

基于位函数的引入与介质参量无关,将各向异性目标内外的电场展为级数形式,得到了任意各向异性目标n阶散射场、目标内场的递推表达式,给出了介电常量张量的变换关系,在平面波任意入射的条件下,并给出了传播单位矢量与极化单位矢量的一般关系.以磁化冷等离子体为例,给出了一阶散射场的具体表达式,并对二阶散射场引起的误差进行了评估.在THz波段和光波段,对所得结果进行了部分仿真.结果表明:微分散射对电波频率和极化状态等因素的影响较为敏感,介电常量张量的非对角元素对散射的影响不大,当波长与目标尺寸一定时,仿真结果不仅适用于THz波段,对其它波段也成立.     

磁化冷等离子体球的太赫兹散射特性

基于位函数的引入与介质参量无关,将各向异性目标内外的电场展为级数形式,得到了任意各向异性目标n阶散射场、目标内场的递推表达式,给出了介电常量张量的变换关系,在平面波任意入射的条件下,并给出了传播单位矢量与极化单位矢量的一般关系.以磁化冷等离子体为例,给出了一阶散射场的具体表达式,并对二阶散射场引起的误差进行了评估.在THz波段和光波段,对所得结果进行了部分仿真.结果表明:微分散射对电波频率和极化状态等因素的影响较为敏感,介电常量张量的非对角元素对散射的影响不大,当波长与目标尺寸一定时,仿真结果不仅适用于THz波段,对其它波段也成立.     

Relativistic Magnetosonic Soliton in a Negative-Ion-Rich Magnetized Plasma

Two-dimensional (2D) relativistic magnetosonic solitons in the negative-ion-rich plasma consisting of positive ions Ar⁺, negative ions SF₆^- and electrons are investigated in the presence of an applied magnetic field B₀ and can be described by a Kadomtsev--Petviashvili (KP) equation in the weakly relativistic limit. The ratio of positive ion density to negative ion density has a marked influence on the amplitude Φ_m and width W of the steady-state KP soliton. The interaction law of the nontrivial solitons with rich web structure is studied by the Wronskian determinant method.     

Oblique Electron Thermal Waves in a Magnetized Plasma

Propagations of an oblique electron thermal mode under the electron plasma frequency without boundary effects are investigated experimentally and theoretically in a magnetized plasma. The phase, ray, and group velocity surfaces of the electron thermal mode are obtained in a polar coordinate. The experimental observation of the electron mode radiated from a point source is found to be in fair accord with the theoretical wave fronts which are obtained from the ray velocity surface. Wave fronts and ray trajectories of an oblique electron thermal mode radiated from a point source are numerically obtained in an inhomogeneous magnetized plasma with a use of an electrostatic kinetic theory. The spatial numerical results are indicated mainly below the electron plasma and cyclotron frequencies. Reflections of the mode in the plasma density lower than the electron plasma frequency are made clear numerically.     

The Ponderomotive Force on a Charge q,Moving in an Electromagnetic Field

Equations of motion of a single charged particle are derived to second order in E where E is an electromagnetic field. By averaging over the wave-period we find the ponderomotive force on the particle. This force may lead to a transport of matter as is also the case in ordinary hydrodynamics. There the effect is called acoustic streaming. We also suggest that the well-known Landau damping may be considered as beeing due to a ponderomotive force.