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.     

各向异性磁化等离子体JEC-FDTD算法

将色散介质的电流密度卷积-时域有限差分(JEC-FDTD)算法推广到各向异性磁化等离子体色散介质.该算法同时解决了电磁波在各向异性和频率色散介质中传播的难题，给出了各向异性磁化等离子体JEC-FDTD算法的公式.计算磁化等离子体平板对平行于磁场传播的电磁波的反射和透射系数，通过与解析结果的比较，验证了该算法的高效性和高精度. 关键词： 色散介质 FDTD算法 各向异性 磁化等离子体     

Dust-lower-hybrid waves in quantum plasmas

The dispersion relation of the dust-lower-hybrid wave has been derived using the quantum hydrodynamic model of plasmas in an ultracold Fermi dusty plasma in the presence of a uniform external magnetic field. The dust dynamics, electron Fermi temperature effect, and the quantum corrections give rise to significant effects on the dust-lower-hybrid wave of the magnetized quantum dusty plasmas.     

Two‐dimensional magnetosonic shock wave propagation in dense electron–positron–ion plasmas

Two‐dimensional (2D) magnetosonic wave propagation in magnetized quantum dissipative plasmas is studied. The plasma system is comprised of inertial ions, inertia‐less electrons, and positrons. The multi‐fluid quantum hydrodynamic model is used, in which quantum statistical and quantum tunnelling effects of electrons and positrons are included. Reductive perturbation analysis is performed to derive the Zabolotskaya–Khokhlov equation for the 2D propagation of a magnetosonic shock wave in a magnetized qauntum plasma. The effects of varying the different plasma parameters such as positron density and magnetic field intensity on the propagation characteristics of magnetosonic shock waves are discussed with non‐relativistic degenerate plasma parameters in astrophysical plasma situations.     

Plasma-Maser Instability of Bernstein Mode in Presence of Magnetohydrodynamic Turbulence

A theoretical study is made on the amplification mechanism of electrostatic Bernstein mode wave in presence of kinetic Alfven wave turbulence in a magnetized plasma on the basis of plasma-maser interaction. It is shown that a test high frequency electrostativ Bernstein mode wave is unstable in the presence of low frequency kinetic Alfven wave turbulence. The growth rate of the Bernstein wave vanishes only in an unmagnetized plasma. Because of the universal existence of the kinetic Alfven waves in large scale plasmas, the results have potential importance in space and astrophysical radiation processes.     

Electrostatic Waves in Weakly Magnetized Quantum Plasmas

By using the quantum magnetohydrodynamic model, the electrostatic waves in weakly magnetized quantum plasmas are investigated. The electrons are treated as a quantum and magnetized species, while the ions are classical unmagnetized ones. The general dispersion relations are derived. It is shown that, both the high frequency electron waves （Langmuire wave and upper-hybrid wave） and the low frequency ion acoustic wave can propagate when the plasmas are cold.     

磁化等离子体光子晶体的FDTD分析

磁化等离子体光子晶体是磁化等离子体和介质(真空)构成的人工周期性结构.本文用磁化等离子体的分段线形电流密度卷积(PLCDRC)时域有限差分(FDTD)算法分析了磁化等离子体光子晶体特性.分析了磁化等离子体参数对电磁带隙的影响.从时域的角度分析了高斯脉冲在磁化等离子体光子晶体中的传播过程，给出了时域反射和透射波形.从频域的角度给出了磁化等离子体光子晶体的电磁反射系数和透射系数，并对结果进行了分析. 关键词： 磁化等离子体 光子晶体 时域有限差分法     

FDTD Analysis of Electromagnetic Reflection by Conductive Plane Covered with Magnetized Inhomogeneous Plasmas

A novel finite-difference time-domain (FDTD) methodology which incorporates both anisotropy and frequency dispersion at the same time is developed for electromagnetic wave propagation in anisotropic magnetoactive plasmas in this paper. The numerical verification of the method are confirmed by computing the reflection and transmission of right-handed/left-handed circularly polarized (RCP/LCP) wave through a magnetized plasma layer, with the direction of propagation parallel to the direction of the biasing field. And, the right-handed / left-handed polarized wave reflection coefficients for electromagnetic signals normally incident upon a conductive plane covered with a layer of magnetized plasma are computed using the new FDTD method. The parabolic electron-number density profile varies only in the direction perpendicular to the plane. The function dependence of reflection coefficients on the number density, collision frequency and external magnetic field is studied.     

An exact solution of the relativistic equation of motion of acharged particle driven by a circularly polarized electromagnetic waveand a constant magnetic field

An exact solution is found for the relativistic equation of motion of a charged particle driven by a circularly polarized electromagnetic wave and a constant magnetic field. The explicit expressions of particle position and velocity are obtained for certain initial conditions. The results are of interest to the interaction of the high-power laser with the magnetized plasma, electromagnetically pumped free-electron laser with a guide magnetic field, propagation of electromagnetic wave signals through a re-entry plasma sheath in the presence of a strong magnetic field, and magnetic confinement plasmas     

等离子体加载耦合腔慢波结构色散分析

利用磁化等离子体介电张量和纵向场分量法对任意大小轴向磁场中等离子体填充耦合腔慢波结构进行场分析，得到磁化等离子体填充电子注通道电磁波场分量的轴对称精确解.在此基础上，建立耦合腔分区模型、采用场匹配方法建立色散方程，并数值计算得出不同等离子体密度及磁场下的耦合腔色散曲线.对不同密度等离子体填充情况下的耦合腔色散特性、混合模式的形成机理以及等离子体空间电荷波进行了分析讨论. 关键词： 耦合腔慢波结构 等离子体 混合模式 色散特性     

Plasma-maser interaction of langmuir wave with kinetic Alfvén wave turbulence

A theoretical study is made on the generation mechanism of Langmuir mode wave in the presence of kinetic Alfvén wave turbulence in a magnetized plasma on the basis of plasma-maser interaction. It is shown that a test high frequency Langmuir mode wave is unstable in the presence of low frequency kinetic Alfvén wave turbulence. The growth of the Langmuir wave occurs due to direct and polarization coupling terms. Because of the universal existence of the kinetic Alfvén waves in large scale plasmas, the results have potential importance in space and astrophysical radiation processes.     

Ion acceleration by the space charge electric force arising from the radiation pressure in a magnetized electron–positron plasma

It is shown that ions can be accelerated by the space charge electric force arising from the separation of electrons and positrons due to the ponderomotive force of the magnetic field-aligned circularly polarized electromagnetic (CPEM) wave in a magnetized electron–positron–ion plasma. The ion acceleration critically depends on the external magnetic field strength. The result is useful in understanding differential ion acceleration in magnetized electron–positron–ion plasmas, such as those in magnetars and in some laboratory experiments that aim to mimic astrophysical environments.     

时变磁化等离子体光子晶体光子局域态分析

采用磁化等离子体的分段线形电流密度卷积(Piecewise Linear Current Density Recursive Convolution,PLCDRC)时域有限差分(Finite-Different Time-Domain,FDTD)算法研究了具有单一缺陷层一维时变磁化等离子体光子晶体的光子局域态特性。以高斯脉冲为激励源,用算法公式所得的电磁波透射系数来讨论了等离子体上升时间对其缺陷模的影响。结果表明,改变等离子体上升时间和密度可以获得不同的缺陷模。     

温度、密度对磁化等离子体光子晶体缺陷模的影响

采用等温近似,用磁化等离子体的分段线形电流密度卷积(Piecewise Linear Current Density Recursive Convolution,PLCDRC)时域有限差分(Finite-differentce Time-domain,FDTD)算法研究了具有单一缺陷层的一维磁化等离子体光子晶体的缺陷模特性;以高斯脉冲为激励源,用算法公式计算所得的电磁波透射系数,讨论了温度和等离子体层密度对其缺陷模的影响。结果表明:改变温度和等离子体层密度可以获得不同的缺陷模。     

时变磁化等离子体光子晶体的禁带特性

采用磁化等离子体的分段线形电流密度卷积(Piecewise Linear Current Density Recursive Convolution,PLCDRC)时域有限差分(Finite-Different Time-Domain, FDTD)算法研究了一维时变磁化等离子体光子晶体的禁带特性。以高斯脉冲为激励源,用算法公式所得的电磁波透射系数来讨论了等离子体上升时间、密度、周期常数对其禁带特性的影响。结果表明,改变等离子体上升时间和密度可以实现对禁带的控制。     

Higher-order inertial Alfvén wave dressed solitons,quasiperiodic structures,and chaos in plasmas

The higher-order, low-amplitude inertial Alfvén wave (IAW) dressed soliton and chaos are investigated in a magnetized plasma. In the linear limit, the dispersion relation for propagation of IAWs in plasmas is also obtained in the presence of electron thermal effects and illustrated numerically. It is found that the electron inertial length plays an important role for wave dispersion effects and its phase speed is increased on including the electron temperature in the model. The reductive perturbation method is employed to obtain the first-order IAW Korteweg–de Vries (KdV) soliton and second-order dressed soliton solutions analytically, which gives electron density dip (or rarefactive) structure and moves with super Alfvénic speed in plasmas. The numerical illustrations of the KdV and dressed IAW solitons are also presented by using the laboratory and space plasma parameters given in the literature. Furthermore, a numerical study of quasi-periodicity and chaotic behaviour of IAWs in the presence of external periodic force is also discussed in detail. The effects of plasma beta (which depends on plasma density, electron temperature, and magnetic field intensity) and obliqueness of the wave propagation on the formation of nonlinear Alfvénic wave structures have also been presented.     

Manipulating electromagnetic waves in magnetized plasmas: compression, frequency shifting, and release

A new approach to manipulating the duration and frequency of microwave pulses using magnetized plasmas is demonstrated. The plasma accomplishes two functions: (i) slowing down and spatially compressing the incident wave, and (ii) modifying the propagation properties (group velocity and frequency) of the wave in the plasma during a uniform in space adiabatic in time variation of the magnitude and/or direction of the magnetic field. The increase in the group velocity results in the shortening of the temporal pulse duration. Depending on the plasma parameters, the frequency of the outgoing compressed pulse can either change or remain unchanged. Such dynamic manipulation of radiation in plasma opens new avenues for manipulating high power microwave pulses.     

Taming Drift Wave Turbulence

Drift waves in magnetized plasmas often occur in a turbulent form and are often considered as being responsible for anomalous cross‐field particle transport. It is thus very appealing to achieve active control of the drift wave dynamics. A control scheme acting both in space and in time is developed to synchronize drift wave turbulence. It consists of an arrangement of eight electrodes (octupole exciter) in flush‐mounted geometry in the edge region of the magnetized plasma column. The electrodes of the octupole exciter are driven by sinusoidal signals. Between each two neighbouring electrodes, the phase shift of the exciter signal is kept fixed. It is demonstrated experimentally that the exciter signals have strong influence on the different drift wave states, i.e. the turbulent states can be synchronized to a single preselected drift wave mode. The efficiency of the spatiotemporal synchronization is sensitively dependent on both driver frequency and phase shift.     

Quantum-electrodynamical photon splitting in magnetized nonlinear pair plasmas

We present for the first time the nonlinear dynamics of quantum electrodynamic (QED) photon splitting in a strongly magnetized electron-positron (pair) plasma. By using a QED corrected Maxwell equation, we derive a set of equations that exhibit nonlinear couplings between electromagnetic (EM) waves due to nonlinear plasma currents and QED polarization and magnetization effects. Numerical analyses of our coupled nonlinear EM wave equations reveal the possibility of a more efficient decay channel, as well as new features of energy exchange among the three EM modes that are nonlinearly interacting in magnetized pair plasmas. Possible applications of our investigation to astrophysical settings, such as magnetars, are pointed out.