Nonstationary motion of electrons in a double plasma layer subjected to the self-consistent electric field of the space charge

Nonstationary 1D equations describing the motion of electrons in a double plasma layer subjected to the self-consistent electric field of the space charge are investigated with allowance for friction force. Analytical solutions to a set of nonlinear hydrodynamic equations for plasma electrons are derived. The variation of the electric field strength, as well as of the electron velocity and concentration, in space and time is found. Electron plasma motions of different types of symmetry are characterized in terms of dynamic parameters.     

Gauge treatment of the intra-collisional-field-effect in electron transport theory

We study the evolution equations of the distribution functions of hot electrons. We show that a convenient choice of the gauge describing the applied uniform electric and magnetic fields considerably simplifies the explicit calculations. The main advantage of our method lies in the possibility of treating with the same simplicity free electrons (with or without a magnetic field) and Bloch electrons (without a magnetic field). We discuss the influence of the electric field on the collision term of the different transport equations we derive.     

RF electric field penetration and power deposition into nonequilibrium planar-type inductively coupled plasmas

The RF electric field penetration and the power deposition into planar-type inductively coupled plasmas in low-pressure discharges have been studied by means of a self-consistent model which consists of Maxwell equations combined with the kinetic equation of electrons. The Maxwell equations are solved based on the expansion of the Fourier--Bessel series for determining the RF electric field. Numerical results show the influence of a non-Maxwellian electron energy distribution on the RF electric field penetration and the power deposition for different coil currents. Moreover, the two-dimensional spatial profiles of RF electric field and power density are also shown for different numbers of RF coil turns.     

外加静电场的聚焦激光脉冲真空加速电子方案

采用五阶修正的聚焦激光光场方程模拟研究了由Singh提出的在电子和激光脉冲作用尾部阶段施加外场的加速方案,将Singh方案中采用的外加磁场改成了外加电场,并且考虑了光束的纵向电场和光束衍射效应.模拟结果显示,电子可以从加速相位阶段被外场导入下一个加速相位阶段而不进入减速相位阶段,因此电子能获得比不加外场方案更高的净能增益. 关键词： 强激光 激光加速     

New interior solution describing relativistic fluid sphere

Nonlinear low-frequency electrostatic waves in a magnetized, three-component plasma consisting of hot electrons, hot positrons and warm ions have been investigated. The electrons and positrons are assumed to have Boltzmann density distributions while the motion of the ions are governed by fluid equations. The system is closed with the Poisson equation. This set of equations is numerically solved for the electric field. The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are sinusoidal, sawtooth and spiky. The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E ₀ was reduced. The results are compared with satellite observations.     

Magnetic field-aligned plasma expansion in critical ionizationvelocity space experiments

The temporal evolution of a plasma cloud released in an ambient plasma is studied. Time-dependent Vlasov equations for both electrons and ions, as well as the self-consistent electric field parallel to the ambient magnetic field, are solved. The initial cloud is considered to consist of cold, warm, and hot electrons with temperatures of approximately 0.2 eV, 2 eV, and 10 eV, respectively. It is found that the minor hot electrons escape the cloud; their velocity distribution function shows the typical time-of-flight dispersion feature, i.e. the average drift velocity of the escaping electrons is proportional to the distance from the cloud. The major warm electrons expand along the magnetic field lines with the corresponding ion-acoustic speed. The combined effect of the escaping hot electrons and the expanding warm ones sets up an electric potential structure that accelerates the ambient electrons into the cloud. Thus, the energy loss due to the electron escape is partly replenished. The electric field distribution in the potential structure depends on the stage of the evolution; before the rarefaction waves propagating from the edges of the cloud reach its center, the electric fields point into the cloud. After this stage the cloud divides into two subclouds, each having its own bipolar electric field. The effects of collisions on the evolution of plasma clouds are also discussed. The relevance of the results seen from the calculations are discussed in the context of space experiments on critical ionization velocity     

Self-Consistent expansion of a layer of electrons in the field of intrinsic space charge against the background of a neutral gas

The dynamics of self-consistent expansion of an electron layer under the action of the electric force of intrinsic space charge and friction force is investigated. The expansion of the electron layer occurs against the background of a neutral gas, which gives rise to the friction force opposing the motion of electrons. One-dimensional motion of electrons is considered for plane, cylindrical, and spherical symmetries. Exact analytic solutions are obtained to the linear system of hydrodynamic equations of plasma for electrons with a self-consistent electric field.     

Electron drift velocity and mobility in graphene

We present a theoretical study of the electric transport properties of graphene-substrate systems. The drift velocity, mobility, and temperature of the electrons are self-consistently determined using the Boltzmann equilibrium equations. It is revealed that the electronic transport exhibits a distinctly nonlinear behavior. A very high mobility is achieved with the increase of the electric fields increase. The electron velocity is not completely saturated with the increase of the electric field. The temperature of the hot electrons depends quasi-linearly on the electric field. In addition, we show that the electron velocity, mobility, and electron temperature are sensitive to the electron density. These findings could be employed for the application of graphene for high-field nano-electronic devices.     

Interaction of ultrashort light pulses with carbon nanotubes

The possibility of existence of electromagnetic solitons in carbon nanotubes is investigated on the basis of the coupled equations for the classical distribution function of electrons in such nanotubes and the Maxwell equations for electromagnetic fields. Solitons arise due to the matched change in the classical distribution function and the electric field formed by nonequilibrium electrons of a carbon nanotube. The data of numerical calculations, indicative of the existence of solitons, are reported.     

驻波加速管中的电子反轰现象

在以半腔为首腔的边耦合驻波加速管中观察到了电子反轰现象,由于电子反轰的结果,导致电于枪发射电流非正常增长。本文从纵向运动方程出发,用相轨道方法分析了驻波加速管中的电子反轰运动,并计算了不同电场分布、不同电场幅值及不同注入电压对电子反轰的影响。     

110 GHz微波电离大气产生等离子体过程的理论研究

将描述电磁波的Maxwell方程组和简化的等离子体流体方程组耦合数值求解,对110 GHz微波电离大气产生等离子体的过程进行了理论研究. 研究发现:在高气压下等离子体成丝状;中等气压下等离子体先成丝状,在向微波源移动的过程中逐渐向连续的等离子体区域过渡;低气压下电离产生连续的等离子体区域. 不同气压下等离子体区域都向微波源方向移动. 初始电子数密度分布只影响放电初始阶段的等离子体区域形状,不会影响成丝与否. 等离子体区域在垂直于电场方向和平行于电场方向的移动规律不同. 当电场平行于计算平面时,由于沿着电场方向等离子体两端存在强场区,等离子体区域被拉长,在较低的气压下会出现等离子体丝阵. 关键词： 110 GHz微波 大气电离 等离子体丝阵     

Heating mechanism in one-dimensional bounded magnetized inductively coupled plasma

A self-consistent nonlocal kinetic model has been established to investigate the electron heating mechanism in an one-dimensional bounded magnetized inductively coupled plasma (MICP) under low pressures. The interaction function of electrons with rf electric field and electron energy distribution function (EEDF) are determined by solving the linearized Boltzmann equation incorporating with the Maxwell equations. The numerical results show that the presence of the direct-current (dc) magnetic field plays an important role in the EEDF and high-energy electrons are efficiently heated by the Azbel–Kaner resonances under the anomalous skin-effect conditions.     

The exact solutions of Kane equations which have position-dependence band gap in an external non-uniform electric field

The energy spectrum of electrons in narrow band gap semiconductor nanocrystals which have position dependence band gap in an external non-uniform electric field which compensate the position dependence of the band edge of the valence band potential are studied theoretically taking into account the non-parabolicity of electrons in dispersion laws. The exact solutions of the Kane equations with strong spin–orbital interaction are determined with and without magnetic field via the band gap changes as a function of the position. The position dependence of the band gap is taken parabolically.     

Electron Density and Temperature Rise Time of a Weakly Ionized Oxygen Plasma Subject to an Alternating Electric Field

Macroscopic balance equations for particle number, momentum and energy of the electrons are derived from the Boltzmann equation which describe the time evolution of a weakly ionized oxygen plasma exposed to an alternating homogeneous electric field. The equations are applied to estimate the rise time of electron temperature and density when a rf pulse is emitted from a satellite into the ionospheric plasma.     

Non-linear high-frequency waves in the magnetosphere

Using fluid theory, a set of equations is derived for non-linear high-frequency waves propagating oblique to an external magnetic field in a three-component plasma consisting of hot electrons, cold electrons and cold ions. For parameters typical of the Earth’s magnetosphere, numerical solutions of the governing equations yield sinusoidal, sawtooth or bipolar wave-forms for the electric field Article presented at the International Conference on the Frontiers of Plasma Physics and Technology, 9–14 December 2002, Bangalore, India.     

Dynamical Processes on Complex Networks,by A. Barrat,M. Barthélemy and A. Vespignani

The present state of theory and experiment on the gravity-induced electric field in metallic conductors and the electric field in accelerated metal conductors is reviewed. The relevant equations are derived in very simple approximations. The results depend on whether the deformation of the lattice of positive ions is neglected or is taken into account. Experimental results obtained with freely falling electrons in a cavity in the metal do not agree with the measurements of potentials on rapidly spinning metal rotors. Older direct measurements of the specific charge of carriers in metallic conductors are also mentioned.     

Certain general questions of fast-electron transport II. Kinetic equations and conditions governing the accelerated motion of fast electrons in dielectrics in an electric field

A general kinetic equation for the differential density of fast particles moving in a medium in an external field is derived on the basis of the continuity equation in phase space. An equation is written for the differential flux in the case of fixed target particles. This equation is used to derive equations for fast electrons; account is taken of the coupling of energy-loss and scattering events in an electric field for various particular problems analogous to those studied in the theory of electron transport in the absence of a field. The kinetic equations are used to analyze the conditions governing accelerated motion of electrons in a dielectric in an external electric field in the continuous-deceleration approximation. Account is taken of fluctuations in the energy loss and of multiple scattering. There are two energy ranges of particles moving in a dielectric in which accelerated motion can occur; in the case of an electron beam with a continuous energy spectrum, this acceleration would be accompanied by monochromatization of the beam.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 7–12, February, 1972.     

柱二维内电磁脉冲的自洽计算方法(Ⅲ)

本文是[1]、[2]两篇的续篇,也是这一工作的最后一篇。其主要内容是用拉格朗日方法求解初级电子数方程组,同时给出用PIC方法、欧拉方法和该方法的数值计算结果。并把这些计算结果同非自洽方法的计算结果作了比较。当场强比较高(E>10⁵V/m)时,自洽方法自身的计算结果比较接近。当场强比较低(E≤10⁵V/m)时,两类方法的计算结果符合较好。     

Electromagnetic solitons in bundles of zigzag carbon nanotubes

The possibility of forming solitons in zigzag carbon nanotubes is investigated using the coupled equations for the classical function of the electron distribution and the Maxwell equations for an electromagnetic field. It is demonstrated that the solitons are generated as a result of correlated changes in the classical distribution function and the electric field induced by nonequilibrium electrons of a carbon nanotube. The effective equation describing the dynamics of the electromagnetic field is derived. The existence of solitons is confirmed by the results of numerical calculations. The characteristics of solitons are investigated as a function of the diameter of zigzag carbon nanotubes.