非热离子对非均匀碰撞热尘埃等离子体中三维孤波的影响

从理论上研究了非热离子、外部磁场、碰撞对非均匀热尘埃等离子体中三维非线性尘埃声孤波的影响。运用约化摄动法得到描述三维非线性尘埃声孤波的非标准的变系数Korteweg-de Vries(KdV)方程。然后把非标准KdV方程变为标准的变系数KdV方程,并且得到了标准的变系数KdV方程的近似解析解。由此解析解可以看出,非热离子的数目、碰撞、非均匀性、波的斜向传播、尘埃颗粒和非热离子的温度对三维非线性尘埃声孤波的振幅和宽度有很大的影响。外部磁场对三维非线性尘埃声孤波的宽度有影响,而对其振幅没有影响。此外,波的相速度与非热离子、波的斜向传播、尘埃颗粒的温度和非均匀性有关。     

Cylindrical and spherical Gardner solitons and double layers in a dusty electronegative non-thermal plasma with two-temperature electrons

A precise theoretical investigation has been made on the cylindrical and spherical (nonplanar) Gardner solitons (GSs) and double layers (DLs) in a dusty electronegative plasma (composed of inertial positive and negative ions, Maxwellian cold electrons, non-thermal hot electrons, and negatively charged static dust). The reductive perturbation method has been used in derivation of the modified Gardner (MG) equation describing the nonlinear propagation of the dust ion-acoustic (DIA) waves. The MG equation admits solitary waves (SWs) and DLs solutions for σ around its critical value σ c (where σc is the value of σ corresponding to the vanishing of the nonlinear coefficient of the Korteweg de-Vries (K-dV) equation). The nonplanar SWs and DLs solutions are numerically analyzed and the parametric regimes for the existence of the positive as well as negative SWs and negative DLs are obtained. The basic features of nonplanar DIA SWs and DLs, which are found to be different from planar ones, are also identified. The implications of our results to different space and laboratory dusty plasma situations, are discussed.     

离子与尘埃相互作用对离子声波和尘埃声波的影响

基于流体力学方程和与时间相关的线性微扰理论,分析了尘埃等离子体环境中离子与尘埃粒子的相互作用对离子声波和尘埃声波的影响,结果表明两者间的相互作用使得离子声波变得稳定而使尘埃声波变得不稳定。     

非均匀磁场中的剪切阿尔芬波涡旋

本文研究了非均匀磁场中非线性剪世阿尔芬波，研究表明，在非均匀磁场情况下，阿尔芬波通过自相互作用也可以形成避域涡旋结构。磁场的非均匀性将导致传播区的展宽。     

非同轴双束激光产生的等离子体辐射

采用非同轴双束激光，可得到时空差可控的二束不同性质的等离子体，实现在绝对同等条件下研究多束等离子体辐射的空间非均匀性和等离子体喷射对线加宽的影响。实验结果显示出在最简单的实验装置上实现等离子体强Ｘ射线泵浦Ｘ射线激光方案的可能性。     

非均匀纵向场对等离子体平衡的影响

讨论了纵向不均匀磁场导致磁面与等离子的畸变。对于锐边界情形和具有体电流分布情形求解了平衡方程，特别是给出了磁面变形依赖于各参量变化的表达式。     

尘埃等离子体物理

尘埃等离子体物理是近年来发展起来的新的研究领域。本文介绍了尘埃等离子体物理的研究内容，特点及研究近况。     

非均匀磁场约束条件下的电子束空气等离子体特性

为了揭示大气环境电子束等离子体的性质,基于蒙特卡罗程序包Geant4建立了一个包含电离、激发以及轫致辐射等物理过程的计算模型,用于模拟非均匀磁场约束条件下高能强流稳态电子束的输运特性、以及大气环境等离子体的性质。结果表明:非均匀磁场可以有效控制电子束在空气中的输运轨迹,显著降低电子束的发散;随着电子束在空气中行程的增加,电子束能谱开始展宽并向低能区移动;输运装置出口能量损失比电子束射程末端高2个量级,且随着电子束输运距离的增加,等离子体密度降低;等离子体密度的高低与电子束能量直接相关。     

非均匀磁场约束条件下的电子束空气等离子体特性

为了揭示大气环境电子束等离子体的性质,基于蒙特卡罗程序包Geant4建立了一个包含电离、激发以及轫致辐射等物理过程的计算模型,用于模拟非均匀磁场约束条件下高能强流稳态电子束的输运特性、以及大气环境等离子体的性质。结果表明：非均匀磁场可以有效控制电子束在空气中的输运轨迹,显著降低电子束的发散;随着电子束在空气中行程的增加,电子束能谱开始展宽并向低能区移动;输运装置出口能量损失比电子束射程末端高2个量级,且随着电子束输运距离的增加,等离子体密度降低;等离子体密度的高低与电子束能量直接相关。     

Dissipation of Nonlinear Wave in Inhomogeneous Dust Plasma Crystal

A Korteweg-de Vires-type （KdV-type） equation and a modified Nonlinear Schrodinger equation （NLSE） for the dust lattice wave （DLW） are derived in a weakly inhomogeneous dust plasma crystal. It seems that the amplitude and the velocity of the dust lattice solitary waves decay exponentiaJly with increasing time in a dust lattice. The modulational instability of this dust lattice envelope waves is investigated as well. It is found that the waves are modulational stable under certain conditions. On the other hand, the waves are modulationaJ unstable if the conditions are not satisfied.     

Nonlinear electrostatic waves in inhomogeneous dense dusty magnetoplasmas

The nonlinear electrostatic drift waves are studied using quantum hydrodynamic model in dusty quantum magnetoplasmas. The dissipative effects due to collisions between ions and dust particles have also been taken into account. The Korteweg-de Vries Burgers (KdVB) like equation is derived and analytical solution is obtained using tanh method. The limiting cases of KdV type solitary waves, Burger type monotonic shock waves and oscillatory shock solutions are also presented. It is found that both hump and dip type solitary structures are possible in quantum dusty plasmas. However, amplitude and width of the nonlinear structure depend on the dust charge polarity and its concentration in electron-ion quantum plasmas. The monotonic shock like structure is independent of the quantum parameter. It is found that shock strength is increased in the presence of positively charged particles in comparison with negatively charged dust particles. The oscillatory shock structures are also obtained and it is found that change in dust charge polarity only shifts the phase of the oscillatory shock in plasmas. The numerical results are also presented for illustration.     

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.     

Ion acoustic solitary waves with adiabatic ions in magnetized electron-positron-ion plasmas

Linear and nonlinear ion acoustic waves in the presence of adiabatically heated ions in magnetized electron-positron-ion plasmas are studied. The Sagdeev potential approach is employed to obtain the energy integral equation in such a mulitcomponent plasma using fluid theory. It is found that electron density humps are formed in the subsonic region in magnetized electron-positron-ion plasmas. The amplitude of electron density hump is decreased with the increase of hot ion temperature in electron-positron-ion plasmas. However, the increase in positron concentration and obliqueness of the wave increases the amplitude of nonlinear structure. The increase in positron concentration also reduces the width of the nonlinear structure in a magnetized multicomponent plasma. The numerical solutions in the form of solitary pulses are also presented for different plasma cases. The results may be applicable to astrophysical plasma situations, where magnetized electron-positron-ion plasma with hot ions can exist.     

Obliquely propagating dust-acoustic solitary waves in magnetized dusty plasmas with two-temperature Maxwellian ions

The nonlinear propagation of dust-acoustic waves in an obliquely propagating magnetized dusty plasma, containing Maxwellian distributed ions of distinct temperatures (namely lower and higher temperature Maxwellian ions), negatively charged mobile dust grains, and Maxwellian electrons, is rigorously investigated and analyzed by deriving the Zakharov-Kuznetsov equation. It is investigated that the characteristics of the dustacoustic solitary waves are significantly modified by the external magnetic field, relative ion and electron temperature-ratio, and respective number densities of two population of ions. The implications of the results obtained from this analysis in space and laboratory dusty plasmas are briefly discussed.     

Dust acoustic solitary and shock waves in strongly coupled dusty plasmas with nonthermal ions

The Korteweg-de Vries-Burgers (KdV-Burgers) equation and modified Korteweg-de Vries-Burgers equation are derived in strongly coupled dusty plasmas containing nonthermal ions and Boltzmann distributed electrons. It is found that solitary waves and shock waves can be produced in this medium. The effects of important parameters such as ion nonthermal parameter, temperature, density and velocity on the properties of shock waves and solitary waves are discussed.     

Effect of electron inertia on large amplitude solitary waves in presence of kinematic viscosity in dusty plasma

Nonlinear dust acoustic solitary waves in a dusty plasma are studied for nonzero kinematic viscosity. Sagdeev’s potential can be obtain upto any order in ϕ. The existence of soliton solution is determined by pseudopotential approach. It is seen that the electron inertia has a significant effect on the existence of solitary waves in presence of kinematic viscosity.     

Dressed ion acoustic solitary waves in quantum plasmas with two polarity ions and relativistic electron beams

A theory for dressed quantum ion acoustic waves (QIAWs), which includes higher-order corrections when QIAWs are investigated by the reductive perturbation method, is presented for unmagnetized plasmas containing positive and negative ions and weakly relativistic electron beams. The properties of the QIAWs are investigated using a quantum hydrodynamic model, from which a Korteweg–de Vries equation is derived using the reductive perturbation method. An equation including higher-order dispersion and nonlinearity corrections is also derived, and the physical parameter space is discussed for the importance of these corrections.     

Arbitrary amplitude dust-acoustic solitary waves in a dusty plasma with flat-topped ion distribution

The properties of arbitrary amplitude dust-acoustic (DA) solitary waves (SWs) in a dusty plasma containing warm adiabatic dust fluid, isothermal electrons and ions following flat-topped velocity distribution is studied by the pseudo-potential approach. The effects of dust temperature and flat-trapped ions are found to significantly modify the basic features of DA-SWs as well modify the parametric regime for the existence of rarefactive solitary waves. The pseudo-potential for small amplitude limit is also analytically analyzed, and the numerical results are found to agree with analytical results.     

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研究了强耦合尘埃等离子体的尘埃声波的线性色散关系和尘埃声孤波的非线性传播。考虑一个包含电子、离子、正电扰动尘埃颗粒的完全电离的三成分模型等离子体。假定其电子、离子数密度服从玻尔兹曼分布,而大质量的尘埃成分用一组经典流体方程描述,对系统方程进行线性化,得到了尘埃声波的线性色散关系,发现离子的集中参数对色散关系的影响很大。用约化摄动法对系统方程进行展开,得到了描述小振幅孤波的伯格斯方程。基于伯格斯方程研究了尘埃声孤波的基本特性,发现尘埃颗粒的强耦合效应对尘埃声孤波有很大的修正作用。该研究结果有助于理解尘埃空间等离子体中局域波的一些特性。     

Propagation properties of dust-electron-acoustic waves in weakly magnetized dusty nonthermal plasmas

The linear and nonlinear properties of dust-electron acoustic waves (DEAWs) propagating in magnetized, collisionless, dusty plasma system containing inertial cold electrons, Maxwellian hot electrons, nonthermal ions, and arbitrarily (positively or negatively) charged stationary dust are investigated. The reductive perturbation technique is employed to reduce the basic set of fluid equations to the modified Korteweg-de Vries equation or Ostrovsky's equation, which governs the dynamics of small amplitude DEAWs in a weakly magnetized dusty nonthermal plasma. The approximate analytical as well as numerical solutions reveal that the basic characteristics of DEA nonlinear structures are found to be significantly modified by the key plasma configuration parameters. It is found that the leading compressive or rarefactive solitary wave structure separates from a trailing wave packet during a considerable time under the influence of magnetic field-induced Lorentz force.