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提出碰撞吸收型等离子体的等效折射指数,重新计算了折射角,并与利用常规方法得到的折射角进行了比较。分析了等离子体密度和碰撞频率对折射角的影响。考察了斜入射电磁波在吸收型等离子体中的折射特性,并以一维非均匀碰撞吸收型等离子体为例,对斜入射电磁波的反射特性进行了考察。结果表明,等效折射指数的概念涵盖了入射角度的影响,在考察斜入射时更准确、便捷。     

The dielectric tensor and field equations in the inhomogeneous cold collisionless magnetized drift plasmas with elliptical cross sections

In this Letter the dielectric permittivity tensor and field equations in multi layer cold collisionless magnetized inhomogeneous drift plasma columns with confocal elliptical cross sections are investigated. It will be shown that the dielectric tensor of each region can be written as non-operational Hermitian and pure spatial operational parts.     

Kinetic susceptibility and transport theory of collisional plasmas

A system of nonlocal electron transport equations for electrostatic perturbations in (omega,k) space in a high-Z plasma is derived from the Fokker-Planck equation for arbitrary relations between the time, space, and collisionality scales. The closed scheme for obtaining the longitudinal plasma susceptibility epsilon(omega,k) in the entire (omega,k) plane is proposed. Regions in the (omega,k) plane have been mapped for problems such as the relaxation of the local temperature enhancement with a time-dependent heat conductivity. The electron dielectric permittivity has been calculated over the entire range of parameters, including the transition region between Vlasov and Fokker-Planck equation solutions.     

Quantum effects on magnetization due to ponderomotive force in cold quantum plasmas

The quantum effects on the magnetization due to the ponderomotive force are investigated in cold quantum plasmas. It is shown that the ponderomotive force of the electromagnetic wave induces the magnetization and cyclotron motion in quantum plasmas. We also show that the magnetic field would not be induced without the quantum effects in plasmas. It is also found that the quantum effect enhances the cyclotron frequency due to the ponderomotive force related to the time variation of the field intensity. In addition, it is shown that the magnetization diminishes with an increase of the frequency of the electromagnetic field.     

Theoretical calculation of the dielectric tensor and field equations in columns with elliptical cross-sections including inhomogeneous magnetized cold collisionless drift and rotating plasmas

In this paper the effects of the inhomogeneity of the density of charged particles and the initial axial, rotating and radial motion on the dielectric permittivity tensor and the field equations in a long column of multi-layer magnetized plasmas with confocal elliptical cross-sections are investigated. The elements of the dielectric permittivity tensor and the generalized field equations of each region are obtained. The field equations for hybrid modes in each region of the inhomogeneous plasma with coaxial elliptical cylindrical boundaries are presented.     

Wave-particle decorrelation and transport of anisotropic turbulence in collisionless plasmas

Comprehensive analysis of the largest first-principles simulations to date shows that stochastic wave-particle decorrelation is the dominant mechanism responsible for electron heat transport driven by electron temperature gradient turbulence with extended radial streamers. The transport is proportional to the local fluctuation intensity, and phase-space island overlap leads to a diffusive process with a time scale comparable to the wave-particle decorrelation time, determined by the fluctuation spectral width. This kinetic time scale is much shorter than the fluid time scale of eddy mixing.     

高Z等离子体中的双电子复合与电子碰撞激发

采用准相对论性Hartree-Fock-Relativistic方法与不可分辨跃迁组模型相结合,对Au和Ta元素的类Ni离子的双电子复合速率,以及Au元素类Cu离子的电子碰撞激发速率进行了计算。计算结果表明,对于Au类Ni离子的3d10-3d94l5f-3d104l双电子复合过程以及类Cu离子的3d104l-3d94l5f电子碰撞激发过程,当电子温度高于1.0 keV时,电子离子碰撞激发速率随电子温度增加而增加,双电子复合速率随电子温度增加而减小,并且电子碰撞激发对谱线辐射的贡献要比双电子复合大得多。     

高Z等离子体中的双电子复合与电子碰撞激发

 采用准相对论性Hartree-Fock-Relativistic方法与不可分辨跃迁组模型相结合,对Au和Ta元素的类Ni离子的双电子复合速率,以及Au元素类Cu离子的电子碰撞激发速率进行了计算。计算结果表明,对于Au类Ni离子的3d¹⁰-3d⁹4l5f-3d¹⁰4l双电子复合过程以及类Cu离子的3d¹⁰4l-3d⁹4l5f电子碰撞激发过程,当电子温度高于1.0 keV时,电子离子碰撞激发速率随电子温度增加而增加,双电子复合速率随电子温度增加而减小,并且电子碰撞激发对谱线辐射的贡献要比双电子复合大得多。     

Electron hole generation and propagation in an inhomogeneous collisionless plasma

The generation of "trains" of electron holes in phase space due to an external electrostatic disturbance is investigated by using a Vlasov-Ampere code with open boundary conditions. Electron holes are produced mostly during the initial phase of the wave-plasma interaction, with a given drift velocity which is maintained until they exit the integration box, even in the presence of plasma inhomogeneities. They present macroscopic features, a dipolar electrostatic field and an electron density perturbation, which can be exploited for diagnostic purposes. Their equilibrium is intrinsically kinetic, in that they are accompanied by a stationary hole in the electron distribution function.     

On the fluctuations spectrum of inhomogeneous plasmas and fluids

A general formula for the fluctuations spectrum of inhomogeneous plasmas and fluids at statistical equilibrium is found. It is valid for linearized equations of conservative systems and uses a rigorous treatment within Gibbs statistics. It opens the way for quantitative calculations of two-dimensional systems.     

Ion larmour radius effect on rf ponderomotive forces and induced poloidal flow in tokamak plasmas

Analytical approximations are used to clarify the effect of Larmour radius on rf ponderomotive forces and on poloidal flows induced by them in tokamak plasmas. The electromagnetic force is expressed as a sum of a gradient part and of a wave momentum transfer force, which is proportional to wave dissipation. The first part, called the gradient electromagnetic stress force, is combined with fluid dynamic (Reynolds) stress force, and gyroviscosity is included into viscosity force to model finite ion Larmour radius effects in the momentum response to the rf fields in plasmas. The expressions for the relative magnitude of different forces for kinetic Alfven waves and fast waves are derived.     

Particle simulation on electron acceleration process by the laser ponderomotive force in inhomogeneous underdense plasma layers

The mechanism of electron ponderomotive acceleration due to increasing group velocity of laser pulse in inhomogeneous underdense plasma layers is studied by two-dimensional relativistic parallel particle-in-cell code. The electrons within the laser pulse move with it and can be strongly accelerated ponderomotively when the duration of laser pulse is much shorter than the duration of optimum condition for acceleration in the wake. The extra energy gain can be attributed to the change of laser group velocity. More high energy electrons are generated in the plasma layer with descending density profile than that with ascending density profile. The process and character of electron acceleration in three kinds of underdense plasma layers are presented and compared.     

Effects of relativistic and ponderomotive nonlinearities on the interaction of high-power laser beam with an inhomogeneous warm plasma

The influence of relativistic-ponderomotive nonlinearities and the plasma inhomogeneity on the nonlinear interaction between a high-power laser beam and a warm underdense plasma are studied. It is clear that the relativistic ponderomotive force and the electron temperature modify the electron density distribution and consequently change the dielectric permittivity of the plasma. Therefore, by presenting the modified electron density and the nonlinear dielectric permittivity of the warm plasma, the electromagnetic wave equation for the propagation of intense laser beam through the plasma is derived. This nonlinear equation is numerically solved and the distributions of electromagnetic fields in the plasma, the variations of electron density, and plasma refractive index are investigated for two different background electron density profiles. The results show that the amplitude of the electric field and electron density oscillations gradually increase and decrease, during propagation in the inhomogeneous warm plasma with linear and exponential density profiles, respectively, and the distribution of electron density becomes extremely sharp in the presence of intense laser beam. It is also indicated that the electron temperature and initial electron density have an impact on the propagation of the laser beam in the plasma and change the plasma refractive index and the oscillations' amplitude and frequency. The obtained results indicate the importance of a proper choice of laser and plasma parameters on the electromagnetic field distributions, density steepening, and plasma refractive index variations in the interaction of an intense laser beam with an inhomogeneous warm plasma.     

On the quasistatic part of the effective-dielectric-constant tensor of collisionless randomly inhomogeneous plasma

The components of the quasistatic part of the effective-dielectric-constant tensor of a collisionless randomly inhomogeneous plasma are calculated, including those near plasma resonances. In the case of an isotropic plasma, the inhomogeneities are assumed to be arbitrarily oriented ellipsoids with arbitrary anisotropy indices. In the case of an anisotropic plasma, the inhomogeneities are assumed to be infinitely extended along the external magnetic field. A test of such an approximation is formulated, and its use is justified. The formulas obtained should be used for correct determination of the effective-dielectric-constant tensor.Scientific-Research Radio-Physics Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 2, pp. 183–193, February, 1994.     

Nonlinear propagation of fast and slow magnetosonic waves in collisional plasmas

Low-frequency fast and slow magnetosonic waves propagating in electron ion plasmas with damping effects through ions and neutral atoms collisions are investigated. Linear wave analysis is performed to obtain dispersion relation. The reductive perturbation method is applied and it is shown that fast and slow modes of nonlinear magnetosonic wave are governed by damped Korteweg-de Vries (DKdV) equation in the presence of ion neutral collisions in plasmas. The analytical solution of DKdV soliton is presented under the assumption of weak collisional effects and numerical solutions of DKdV equation are also obtained using two-level finite difference scheme with the help of Runge–Kutta method at different plasma parameters. The damping of nonlinear fast and slow magnetosonic wave structures at different times are discussed in the context of space plasma situations where ions and neutral atoms collisions exist.     

Electron and positron nonthermality effects on the formation of damped solitons in collisional multi-component plasmas

Electrostatic damped field characteristics in non-thermal fast positron and electron plasma having fluids of positive and negative pair ions have been discussed when collisional frequencies parameters are taken into account. The damped and forced form of Kadomtsev-Petviashvili (DKP) equations have been obtained. The plasma parameters effects of electron density ratio, the negative ionic density ratio, the pair ionic charge ratio, the density of positron ratio, the collisional frequencies, ion mass ratio and the fast non-thermality on the electrostatic damped and forced field formations, as observed in D-F -ionosphere and laboratory experiments have been investigated.