不均匀等离子体中孤子的传播

假设两种离子的分界面是有限长度并连续变化的,研究了由这两种离子组成的等离子体中孤子的传播.在低阶近似条件下,等离子体声波将由KdV方程或非线性Schrdinger方程来描述,由此给出了准孤子振幅、传播速度等参量在传播过程中的变化. 关键词：     

不均匀等离子体中孤子的反射与透射

用一种新的方法从理论上研究了非均匀等离子体中孤子在不连续点处的反射与透射波.在低阶近似条件下，反射波与透射波均可由KdV方程来描述，并给出了低阶近似情况下，当入射波为单孤子时，反射孤子与透射孤子的个数及其大小. 关键词：     

热尘埃等离子体中(2+1)维尘埃声孤波的传播特征

研究了由尘埃颗粒、电子和非热离子所组成的非磁化热尘埃等离子体中(2+1)维非线性尘埃声孤波的传播特征.首先,利用约化摄动法推导得到了用来描述(2+1)维非线性尘埃声孤波的Kadomtsev-Petviashvili(KP)方程,并采用行波解法进行了定性分析,从而获得了该系统的相图及Sagdeev势方程;然后,利用数学软件的数值模拟分析方法讨论了等温和绝热两种状态下,热尘埃等离子体系统中不同参数对KP方程的非线性系数、色散系数、系统相图、Sagdeev势函数及孤立波解的影响.最终,研究结果表明:等温和绝热状态下,尘埃颗粒的质量、电子和非热离子的温度、数密度及分布状态等多种系统参数对非线性尘埃声孤波的振幅、宽度及波形等传播特征均存在重要影响.     

非均匀磁场尘埃等离子体中颗粒的复杂运动

本文研究了在非均匀磁场尘埃等离子体中不规则尘埃颗粒的复杂运动, 包括圆滚运动、尖头圆滚运动、圆周运动以及波浪运动等. 放置在电极上的圆柱形磁铁的主要作用是改变鞘层的径向分布, 进而对颗粒产生径向约束, 使尘埃颗粒悬浮于圆柱形磁铁周围, 其磁场并不足以磁化颗粒使其做圆滚运动. 通过与球形尘埃颗粒的对比实验发现, 圆滚运动是不规则尘埃颗粒在等离子体中特有的一种运动. 我们提出了一种新的机理: 由于不规则颗粒的自旋而引起的横向反Magnus力对颗粒的圆滚运动起了重要的作用. 文中通过受力分析定性地对实验中观察到的非球形颗粒的各种运动给出了合理的解释.     

离子声孤子在不均匀等离子体中的传播特性

本文考虑了离子的有限温度和离子与中性分子的碰撞,讨论离子声孤子在电离导致的弱不均匀等离子体中的传播特性,得到自洽的非均匀浓度分布N(x),漂移速度分布V(x)和相应的孤子解,数值计算给出孤子幅度、速度、宽度随位置的变化,所得结果合理并与实验相符。 关键词：     

尘埃等离子体

尘埃等离子体物理是近十年里等离子体学科中一个活跃的分支领域之一,带电尘埃广泛存在于空间等离子体、实验室聚变装置、低温等离子体工业应用等众多不同的环境中,并且呈现出相同或相似的性质.这是一种部分或完全电离的等离子体,其基本成分除了电子和离子外,还有(通常)带负电的、且电荷不是常数的微粒.带电颗粒有着与电子和离子完全不同的动力学行为,其与等离子体的相互作用呈现出许多新的物理现象.文章介绍了尘埃等离子体物理的简要发展历史、基本性质和主要研究方向以及最近一些热点问题.     

尘埃等离子体

尘埃等离子体物理是近十年里等离子体学科中一个活跃的分支领域之一，带电尘埃广泛存在于空间等离子体、实验室聚变装置、低温等离子体工业应用等众多小同的环境中，并且呈现出相同或相似的性质．这是一种部分或完全电离的等离子体，其基本成分除了电子和离子外，还有（通常）带负电的、且电荷不是常数的微粒．带电颗粒有着与电予和离子完全不同的动力学行为，其与等离子体的相互作用呈现出许多新的物理现象．文章介绍了尘埃等离子体物理的简要发展历史、基本性质和主要研究方向以及最近一些热点问题．     

量子尘埃等离子体中尘埃充电对尘埃声波的影响

采用流体动力学方程组和尘埃充电方程组成的自洽模型系统,对量子尘埃等离子体中的尘埃声波波动性质进行了研究。通过线性理论分析方法得到系统的尘埃声波波动方程及其色散关系,并对色散关系进行了数值分析。研究表明:充电效应定性地修正了尘埃声波的色散特性,引起尘埃声波的耗散,其耗散强度主要与尘埃等离子体的参数有关。最后,分析了引起尘埃声波耗散的物理原因。     

量子尘埃等离子体中尘埃充电对尘埃声波的影响

采用流体动力学方程组和尘埃充电方程组成的自洽模型系统,对量子尘埃等离子体中的尘埃声波波动性质进行了研究。通过线性理论分析方法得到系统的尘埃声波波动方程及其色散关系,并对色散关系进行了数值分析。研究表明：充电效应定性地修正了尘埃声波的色散特性,引起尘埃声波的耗散,其耗散强度主要与尘埃等离子体的参数有关。最后,分析了引起尘埃声波耗散的物理原因。     

尘埃粒子充放电过程对尘埃等离子体电导率的影响

在只受弱电磁场作用且忽略空间色散的情况下，通过求解含碰撞项的电子的Boltzmann方程及尘埃粒子充放电的Shukla方程，导出了弱电离尘埃等离子体的电导率和介电常数计算公式. 将固体火箭喷焰的有关参数代入公式对电导率进行定量分析，结果表明，尘埃粒子的大小及其浓度对弱电离尘埃等离子体的电导率有明显的影响. 关键词： 尘埃等离子体 Boltzmann方程 Shukla方程 电导率     

Magnetoacoustic solitons in pair-ion fullerene plasma

ABSTRACT

The propagation of magnetoacoustic (fast magnetohydrodynamic) waves in pair-ion (PI) fullerene plasma is studied in the linear and nonlinear regimes. The pair-ion (PI) fullerene plasma is theorized as homogeneous, magnetized, warm and collisionless. Employing multi-fluid magnetohydrodynamic model, the dispersion relation is obtained and wave dispersion effects which appear through ion inertial length are discussed. Using reductive perturbation technique (RPT), the Korteweg–de Vries (KdV) equation is derived and its solution for small but finite amplitude magnetoacoustic solitons propagating in the direction perpendicular to the external magnetic field is presented. The compressive magnetoacoustic soliton (i.e. positive potential pulse) propagating with super Alfvénic speed is obtained in magnetized PI fullerene plasma. The variations in the amplitude and width of the magnetoacoustic soliton structures are also illustrated by using numerical values of the plasma parameters such as ions' density, temperature difference between fullerene ions and magnetic field intensity, which have been taken from the PI plasma experiments already published in the literature.     

尘埃等离子体中非线性波的叠加效应及稳定性问题

研究了小的有限振幅的无磁场尘埃等离子体中的非线性波.在一维情况下由Kortewegde Veries(KdV)方程来描述,考虑了二维情况下尘埃等离子体中尘埃颗粒上电荷的变化效应以及双温度离子效应后,尘埃等离子体受到横向高阶扰动后动力学方程由Kadomtsev-Petviashvili(KP)方程来描述.在此基础上,研究了以任意夹角传播的两个及三个孤立子的相互作用问题,考虑非线性效应后振幅相等的双孤立子在相互作用区域内振幅最大值是单个孤立子振幅的4倍,振幅相等的三孤立子在相互作用区域内振幅最大值是单个孤立子振幅的9倍.研究还表明波的传播方向受到横向高阶扰动后是稳定的.     

Kadomtsev-Petviashvili (KP) Burgers Equation in Dusty Negative Ion Plasmas: Evolution of Dust-Ion Acoustic Shocks

We study the nonlinear propagation of dust-ion acoustic (DIA) shock waves in an un-magnetized dusty plasma which consists of electrons, both positive and negative ions and negatively charged immobile dust grains. Starting from a set of hydrodynamic equations with the ion thermal pressures and ion kinematic viscosities included, and using a standard reductive perturbation method, the Kadomtsev-Petviashivili-Burgers (K-P-Burgers) equation is derived, which governs the evolution of DIA shocks. A stationary solution of the K-P-Burgers equation is obtained and its properties are analysed with different plasma number densities, ion temperatures and masses. It is shown that a transition from shocks with negative potential to positive one occurs depending on the negative ion concentration in the plasma and the obliqueness of propagation of DIA waves.     

The effects of dust temperature and the dust charge variation in a dusty plasma with vortex—like ion distribution

By considering both the dust temperature and the dust charge variation in dusty plasma with vortex-like ion distribution, we obtained a modified Korteweg－de Vries equation. It indicates that the effect of dust charge variation can cause the one-dimensional soliton amplitude to become larger, and the dust temperature can cause the soliton amplitude to become larger as well. Moreover, as the dust temperature increases, the soliton amplitude will increase.     

Shock waves in a rotating non-Maxwellian viscous dusty plasma

A theoretical model is presented to study the characteristics of dust acoustic shock in a viscous, magnetized, rotating dusty plasma at both fast and slow time scales. By employing the reductive perturbation technique, the non-linear Zakharov–Kuznetsov–Burger (ZKB) equation is derived for both cases when the dust is inactive and dynamic (fast and slow time scales). Both electrons and ions are considered to follow the kappa/Cairns distribution. It is observed that in both cases, i.e. when dust is in the background and active, viscosity plays a key role in dissipation for the propagation of acoustic shock. Magnetic field and rotation are responsible for the dispersive term. Superthermality is found to affect significantly the formation of the shock wave along with viscous nature of plasma, whereas the dust charge affects the non-linear coefficient of the ZKB equation. The present investigation may be beneficial to the understanding of the rotating plasma, in particular the experiments being carried out.     

The influence of Landau quantization on the propagation of solitary structures in collisional plasmas

In this work, we study damped ion acoustic solitary wave structures in magnetized dense plasmas. The collisional effects of ions with electrons and neutrals are considered. The trapping effects of electrons and Landau quantization are included in the plasma model under consideration. We assume that magnetic field is quantized such that the condition■ is satisfied. We have derived the damped Korteweg–de Vries(dKdV) equation by using small amplitude reductive perturbation technique. The time-dependent analytical and numerical solutions of the dKdV equation are presented. For numerical solutions we apply a two level finite difference scheme with the help of the Runge Kutta method. The effects of variations of different plasma parameters on the propagation characteristics of damped solitary structures in the presence of collisions are 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.     

Effects of dust size distribution in ultracold quantum dusty plasmas

The effect of dust size distribution in ultracold quantum dusty plasmas are investigated in this paper. How the dispersion relation and the propagation velocity for the quantum dusty plasma vary with the system parameters and the different dust distribution are studied. It is found that as the Fermi temperature of the dust grains increases the frequency of the wave increases for large wave number dust acoustic wave. The quantum parameter of H_d also increases the frequency of the large wave number dust acoustic wave. It is also found that the frequency ω₀ and the propagation velocity v₀ of quantum dust acoustic waves all increase as the total number density increases. They are greater for unusual dusty plasmas than those of the usual dusty plasma.     

Interaction of solitary waves in magnetized warm dusty plasmas with dust charging effects

In consideration of adiabatic dust charge variation, the combined effect of the external magnetized field and the dust temperature on head-on collision of the three-dimensional dust acoustic solitary waves is investigated. By using the extended Poincar\'e--Lighthill--Kuo method, the phase shifts and the trajectories of two solitons after the collision are obtained. The effects of the magnitude and the obliqueness of the external magnetic field and the dust temperature on the solitary wave collisions are discussed in detail.