带电粒子与静电波相互作用单粒子方程的严格解

研究了带电粒子与静电波之间的相互作用,给出了带电粒子运动方程的严格解,得出了粒子的速度的解析表达式,同时推导出了带电粒子被静电波俘获的数学条件,讨论了粒子与波能量交换的物理过程,对现有等离子体物理的教材中相关的问题是一个补充.本文结果对带电粒子加速器、微波管以及基础等离子体问题的研究有一定参考意义.     

超高速碰撞产生等离子体云的粒子能量时空分布

为了研究超高速碰撞产生等离子体的粒子能量对航天器电路中元器件的毁伤,获得超高速碰撞产生等离子体粒子能量的时空分布特性是十分必要的。基于超高速碰撞产生稀薄等离子体中带电粒子的运动速度、等离子体的扩散特点,推导出等离子体的粒子能量密度与带电粒子密度及带电粒子运动速度的关系式。进而通过对超高速碰撞2024-T4铝靶实验采集的原始数据分析,利用Matlab编程得到了超高速碰撞2024-T4铝靶产生膨胀等离子体云物理过程中,等离子体的粒子能量密度与带电粒子持续时间及被测点到碰撞点距离的时空分布规律。     

激光等离子体波电子加速器

本文分别用理论分析和粒子模拟方法讨论了等离子体尾波加速器和拍波加速器的物理机制。结果表明,只要激光等离子体波足够强,加上适当强度的横向磁场,就可以把MeV数量级的电子在公尺距离内加速到GeV数量级的能量。另外,还用粒子模拟方法,研究了激光对热等离子体受激向后喇曼散射产生低相速度的等离子体静电波对低能电子加速的问题,探讨了多级或多波加速的可能性。结果表明,利用激光等离子体波加速器,在一般的实验室条件下,就可获得GeV数量级的高能电子。 关键词：     

等离子体粒子模拟(CIC方法)中消除静电自力处理和它引起的静电能损失

近十多年来,等离子体粒子模拟(CIC方法)发展很快,并给出了很多重要的物理结果。我们编制了一维半粒子云网格法编码,并计算出一些较好的物理结果。 在CIC方法中,如果直接利用泊松方程的离散解求作用在粒子云上的静电力,则产生带电粒子对自身的作用力,称为静电自力。在实用的CIC方法中,首先用泊松方程离散解求出平均场,再用平均场求作用在粒子上的静电力。这种处理完全消除了静电自力,同时引起了静电能损失,能量损失份额随着波长变化。     

基于负氢离子源的全三维PIC/MCC模拟算法研究

在分析负氢离子源中等离子体物理机理基础下, 研究并优化粒子模拟算法, 设计高效的粒子存储方法. 研究并运用粒子碰撞蒙特卡罗方法, 考虑等离子体势以及带电粒子间库仑碰撞, 研制了全三维粒子模拟/蒙特卡罗算法(PIC/MCC). 采用磁荷模型, 运用时域有限差分方法计算多峰磁场, 并结合国外负氢离子源JT-60U, 考虑负氢离子源中主要反应, 对全三维PIC/MCC模拟算法模拟验证.     

动力学阿尔文波的实验研究

动力学阿尔文波是垂直波长接近离子回旋半径或电子惯性长度的短波长色散阿尔文波,由于能在磁等离子体的丝化精细结构和带电粒子能化现象中起重要作用,一直是空间和实验室等离子体物理领域里具有广泛兴趣的研究课题.特别是1990年代后,由于空间卫星探测技术和地面等离子体实验技术的不断发展,特别是一些高分辨空间等离子体探测仪器和地面大型等离子体实验设备投入工作以来,在动力学阿尔文波的实验研究上取得了一系列突破性的重要进展.这不仅在实验上进一步证实了动力学阿尔文波一系列重要的理论特性,也导致了对动力学阿尔文波在磁等离子体动力学现象中重要作用的重新认识,并在从地面实验室等离子体到空间和天体等离子体的广泛领域里再次激发了对动力学阿尔文波的研究兴趣.在这篇综述性报告里,我们将着重介绍自上世纪90年代以来有关动力学阿尔文波实验研究的主要进展,包括在地面实验室大型等离子体装置上进行的实验研究、由科学卫星在空间等离子体中进行的实地测量证认、以及对太阳大气中动力学阿尔文波相关信号的遥测分析.这些实验研究覆盖了动力学阿尔文波物理的各个方面,涉及的内容从动力学阿尔文波的基本色散关系、电磁偏振状态、激发与耗散机制,到非线性相互作用和不同等离子体环境下湍动谱的特性等.这将有助于读者更加全面、完整地理解动力学阿尔文波的物理本质及其相关现象.     

静电波对漂移不稳定性的抑制作用

振幅足够大的静电波在等离子体中可使带电粒子的运动轨道发生改变。利用Vlasov方程和Poisson方程在改变轨道上考察漂移波扰动,得到了色散关系。求解色散关系所得的结果表明,在一定条件下,静电波可抑制不稳定的漂移波。     

封面说明

Plasma一词目前译作“等离子体”，根据《物理学词典》（等离子体物理分册）（1985年，科学出版社）所述：“一般来说，等离子体概念可作如下定义：它是由大量的接近于自由运动的带电粒子所组成的体系，在整体上是准中性的，粒子的运动主要由粒子间电磁相互作用所决定，由于这是长程的相互作用。因而使它显示出集体行为（例如各种振荡与波、不稳定性等）”．对于这样一种物质状态，当时为什么要称为“等离子体”，笔者实在不明白．这种由大量带电粒子组成的体系，既含有大量离子。也含有大量电子，整体上是准中性的，为什么在汉译时要突出“离子”呢？     

等离子体尾场加速器中静电波特性

本文在线性近似下求得了等离子体尾场加速器中静电波的频率特征与增长率,对尾场形成机制作了物理解释。     

对"等离子体"名称的质疑

Plasma一词目前译作“等离子体”，根据《物理学词典》（等离子体物理分册）（1985年，科学出版社）所述：“一般来说，等离子体概念可作如下定义：它是由大量的接近于自由运动的带电粒子所组成的体系，在整体上是准中性的，粒子的运动主要由粒子间电磁相互作用所决定，由于这是长程的相互作用。因而使它显示出集体行为（例如各种振荡与波、不稳定性等）”．对于这样一种物质状态，当时为什么要称为“等离子体”，笔者实在不明白．这种由大量带电粒子组成的体系，既含有大量离子。也含有大量电子，整体上是准中性的，为什么在汉译时要突出“离子”呢？     

The dust acoustic wave in a bounded dusty plasma with strong electrostatic interactions between dust grains

The dispersion relation for the dust acoustic wave (DAW) in an unmagnetized dusty plasma cylindrical waveguide is derived, accounting for strong electrostatic interactions between charged dust grains. It is found that the boundary effect limits the radial extent of the DAW. The present result should be helpful for understanding the frequency spectrum of the DAW in a dusty plasma waveguide with strongly coupled charged dust grains.     

等离子体粒子模拟的静电波谱响应特性

本文系统地分析了等离子体粒子模拟的静电波谱响应特性。我们引入了波谱响应函数的概念,并对有限大小粒子的高斯型、三角型和方块型分布及其在网格点附近的偶极展开,对Poisson方程的有限差分和FFT解法分别导出了响应函数表达式。分析讨论了有限大小粒子形状、宽度和处理方式,空间离散化和Poisson方程求解方法对粒子模拟波谱响应特性的影响及对短波噪声的抑制特性。     

Streaming instability of dust-acoustic mode with helical wavefronts

Making use of the kinetic approach for plasma species, the electrostatic twisted dust-acoustic (DA) waves are studied in a collisionless unmagnetized multi-component dusty plasma consisting of electrons, singly ionized positive ions and charged massive dust grains. The Vlasov-Poisson equations are coupled together to obtain a generalized response function by using the Laguerre-Gaussian (LG) perturbed electrostatic potential and distribution function in the paraxial limit. The dispersive properties and growth rate instability of twisted DA waves are examined with distinct OAM states in a multi-component dusty plasma. Various significant modifications associated with the real wave frequency and growth rate are shown with respect to twist parameter and dust concentration. It is examined that dust concentration enhances the growth rate of twisted DA waves, whereas an increase in twist parameter reduces the growth rate instability. The excitation of twisted DA mode is also found to enhance with streaming speed of inertialess electrons. Our results may be useful for particle transport and trapping phenomena due to wave excitation in laboratory dusty plasmas.     

Electrostatic instability in magnetically confined inhomogeneous plasma driven by nonlinear force

A theoretical investigation on amplification of electrostatic ion acoustic wave in magnetically confined plasma has been presented in this paper. This investigation considers nonlinear wave–particle interaction process, called plasma maser effect, in presence of drift wave turbulence supported by magnetically confined inhomogeneous plasma. The role of associated nonlinear dissipative force in this effect in a confined plasma has been analyzed. The nonlinear force, which arises as a result of resonant interaction between electrons and modulated fields, is shown to drive the instability. Using the ion fluid equation and the ion equation of continuity, the nonlinear dispersion relation of a test ion acoustic wave has been derived, and the growth rate of ion acoustic wave in presence of low frequency drift wave turbulence has been estimated using Helimak data.     

Nonlinear dispersion of stationary waves in collisionless plasmas

A nonlinear dispersion of a general stationary wave in collisionless plasma is obtained in a nondifferential form expressed in terms of a single-particle oscillation-center Hamiltonian. For electrostatic oscillations in nonmagnetized plasma, considered as a paradigmatic example, the linear dielectric function is generalized, and the trapped particle contribution to the wave frequency shift Δω is found analytically as a function of the wave amplitude a. Smooth distributions yield Δω ～ a(1/2), as usual. However, beamlike distributions of trapped electrons result in different power laws, or even a logarithmic nonlinearity, which are derived as asymptotic limits of the same dispersion relation.     

Wave-trapped particle interaction in a weak transverse magnetic field

Damping of an electrostatic plasma wave loaded with a small density bunches of trapped electrons and propagating across a weak magnetic field is studied. To describe the time evolution of the wave, simple algebraic equations are derived under some restrictions on the parameters of the physical system. It is shown that the nonlinear frequency shift of the wave due to the presence of the trapped particles plays an important role and must be taken into account in the self-consistent treatment of the wave–particle interaction.     

Unstable twisted modes in interpenetrating space plasmas containing superthermal species

The electrostatic twisted modes with orbital angular momentum and associated kinetic instability are studied in a permeating space plasma containing streaming particle species. The plasma containing superthermal electrons and ions is modeled by using a non-gyrotropic Kappa distribution function which penetrates through a relatively slow moving (static) plasma and gives rise to dispersion, damping and growth of ion-acoustic mode under various conditions. Using the Vlasov-Poisson model, the solutions of twisted modes are defined by Laguerre-Gaussian mode functions, which decompose the plasma distribution function and electric field into components characterized by the axial and azimuthal wave numbers. The dielectric constant is derived and analyzed for threshold condition of wave dispersion and instability in the presence of helical electric field with illustrations. The wave excitations due to penetration of solar wind into cometary clouds or interstellar electron-ion plasmas is examined.     

Dispersion relation of dust acoustic waves in metallic multi-walled carbon nanotubes

In this paper,a charged multi-walled carbon nanotube(MWCNT),which is surrounded by charged nanoparticles,is modeled as a cylindrical shell of electron-ion-dust plasma.By employing classical electrodynamics formulations and the linearized hydrodynamic model,the dispersion relation of the dust acoustic wave oscillations in the composed system is investigated.We obtain a new low-frequency electrostatic excitation in the MWCNT,i.e.dust acoustic wave oscillations.     

Effective charge of a macroparticle in a non‐isothermal plasma within the Poisson–Boltzmann model

The electrostatic potential distribution around a charged, spherical, finite‐size macroparticle in a non‐isothermal plasma‐like medium is studied numerically within the Poisson–Boltzmann model. It is assumed that plasma consists of electrons and one species of singly charged ions. The effective charge of a macroparticle is calculated and its dependence on the electron to ion temperature ratio as well as on the particle radius and bare charge is considered. Numerical results for the effective charge in an isothermal plasma are compared with known analytical expressions.