New longitudinal waves in electron-positron-ion quantum plasmas

A general quantum dispersion equation for electron-positron(hole)-ion quantum plasmas is derived and studied for some interesting cases. In an electron-positron-ion degenerate Fermi gas, with or without the Madelung term, a new type of zero sound waves are found. Whereas in an electron-hole-ion plasmas a new longitudinal quantum waves are revealed, which have no analogies in quantum electron-ion plasmas. The excitation of these quantum waves by a low-density monoenergetic straight electron beam is examined. Furthermore, the Korteweg-de Vries (KdV) equation for novel quantum waves is derived and the contribution of the Madelung term in the formation of the KdV solitons is discussed.     

轴对称系统等离子体数值模拟电荷、电流分配CIC方法

采用体积加权CIC方法,对轴对称系统等离子体模拟PIC方法中的节点电荷和电流计算进行了详细讨论,推导出节点电荷和电流的计算公式,可用于轴对称系统21／2维等离子体静电PIC模拟和电磁PIC模拟。     

The collision frequency of electron-neutral-particle in weakly ionized plasmas with non-Maxwellian velocity distributions

The collision frequencies of electron-neutral-particle in weakly ionized complex plasmas with the non-Maxwellian velocity distributions are studied. The average collision frequencies of electron-neutral-particle in plasmas are accurately derived. We find that these collision frequencies are significantly dependent on the power-law spectral indices of non-Maxwellian distribution functions and so they are generally different from the collision frequencies in plasmas with a Maxwellian velocity distribution, which will affect the transport properties of the charged particles in plasmas. Numerically analyses are made to show the roles of the spectral indices in the average collision frequencies respectively.     

弱相对论等离子体横向扰动下的离子声孤波

在低阶近似下，得到了描述无磁场相对论热离子等离子体的KP(Kadomtsev-Petviashvilli) 方程.研究表明，相对论热离子等离子中的非线性离子声孤波在高阶横向拢动下是稳定的， 且在相对论热离子等离子体中仅存在压缩型孤波. 关键词： 离子等离子体 孤波 声波 约化摄动法     

Cylindrical and spherical dust ion-acoustic solitary waves in quantum plasmas

Dust ion-acoustic solitary waves in unmagnetized quantum plasmas are studied in spherical and cylindrical geometries. Using quantum hydrodynamic model, the electrostatic waves are investigated in the weakly nonlinear limit. A deformed Korteweg-de Vries (dKdV) equation is derived by using the reductive perturbation method and its numerical solutions are also presented. The quantum diffraction and quantum statistical effects incorporated in the system modifies the characteristics of dust ion-acoustic waves in cylindrical and spherical geometries. The role of stationary dust particles in quantum plasmas are also discussed. It is shown that the cylindrical and spherical dust ion-acoustic solitary waves behave quite differently from one-dimensional planar solitary waves in quantum plasmas.     

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.     

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.     

Dynamics of spin-1/2 quantum plasmas

The fully nonlinear governing equations for spin-1/2 quantum plasmas are presented. Starting from the Pauli equation, the relevant plasma equations are derived, and it is shown that nontrivial quantum spin couplings arise, enabling studies of the combined collective and spin dynamics. The linear response of the quantum plasma in an electron-ion system is obtained and analyzed. Applications of the theory to solid state and astrophysical systems as well as dusty plasmas are pointed out.     

On the parametric excitation of surface oscillations of a cold plasma

The excitation of surface oscillations of cold plasmas is studied for external electric fields perpendicular to the plasma density gradient. Boundary conditions for electromagnetic fields on the plane boundary between plasmas with different densities are derived, and the dispersion relation for the excitation of the surface modes is obtained. The effects of metallic walls of a vacuum chamber are considered, together with the excitation of surface oscillations of a plasma slab immersed in a plasma with different density.     

Dispersion of multi-stream instability in quantum magnetized hot plasmas

Using the quantum hydrodynamic (QHD) equations with magnetic field on the Wigner-Maxwell system, the general dielectric tensor and dispersion equation for quantum plasmas were derived. Dispersion relations of one-, two-stream and beam-plasma instabilities in uniform quantum magnetized plasmas are investigated through the new dielectric tensor. The magnetic field which is parallel to the fluid velocity does not work on stream instabilities. The quantum and thermal effects have remarkable impact on two-stream instability. The critical wave number for beam-plasma instability with quantum effects correction is given too.     

Thermodynamic functions of Coulomb systems

Thermodynamic functions are needed for the discussion of phase transitions in gaseous and solid state plasmas. In this paper detailed numerical data for the Hartree-Fock and the Montroll-Ward (ring sum) contributions to the pressure for symmetrical multicomponent plasmas are given at any degree of degeneration.For the Montroll-Ward pressure especially also isotherms are given. There is good agreement with limiting results derived analytically.     

Polarized Debye Sheath in Degenerate Plasmas

The force on a charged dust grain in a plasma due to polarization of thermal ions and degenerate electrons around the grain is derived in the limits of weakly relativistic and ultra-relativistic degeneracy of electrons. It is found that in both these cases, the magnitude of the polarization force is enhanced compared to that in classical plasmas. The influence of this force on dust-acoustic(DA) modes is examined and discussed. It is shown that the DA wave frequency in degenerate plasmas is significantly reduced compared to the classical DA mode.     

Electrostatic Solitary Waves in Pair-ion Plasmas with Trapped Electrons

Electrostatic solitons in an unmagnetized pair-ion plasma comprising adiabatic fluid positive and negative ions and non-isothermal electrons are investigated using both arbitrary and small amplitude techniques. An energy integral equation involving the Sagdeev potential is derived, and the basic properties of large amplitude solitary structures are investigated. Various features of solitons differ in different existence domains. The effects of ion adiabaticity, particle concentration, and resonant electrons on the profiles of Sagdeev potential and corresponding solitary waves are investigated. The generalized Korteweg-de Vries equation with mixed-nonlinearity is derived by expanding the Sagdeev potential. Asymptotic solutions for different orders of nonlinearity are discussed for solitary waves. The present work is applicable to understanding the wave phenomena and associated nonlinear electrostatic perturbations in pair/bi-ion plasmas which may occur in space and laboratory plasmas.     

Energy confinement time and heat transport in initial neutral beam heated plasmas on the large helical device

The confinement characteristics of large net-current-free plasmas heated by neutral-beam injection have been investigated in the Large Helical Device (LHD). A systematic enhancement in energy-confinement times from the scaling derived from the medium-sized heliotron/torsatron experiments have been observed, which is attributed to the edge pedestal. The core confinement is scaled with the Bohm term divided by the square root of the gyro radii. The comparative analysis using a dimensionally similar discharge in the Compact Helical System indicates gyro-Bohm dependence in the core and transport improvement in the edge region of LHD plasmas.     

等离子体交换不稳定性的模耦合理论

本文研究部分电离等离子体中交换不稳定性的爆炸型模耦合。从磁流体动力学方程出发,导出交换模相干三波相互作用的模耦合方程,分析产生爆炸不稳定的可能的耦合类型,具体讨论产生爆炸不稳定的条件。结果表明,非线性效应能使交换模达到饱和状态表现为小幅度的正弦型扰动,也能通过模耦合而导致大幅度扰动的爆发。本文的分析,适用于磁镜位形的等离子体和电离层等离子体。 关键词：     

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     

Modulational instability of ultra-intense linearly polarized laser pulse in electron–positron plasmas

Based on the wave equation of ultra-intense linearly polarized laser pulse propagating in electron–positron plasmas, the modulational instability is investigated. The nonlinear dispersion relation and the growth rate of instability are derived. The effects of plasmas number density, temperature, and laser intensity on the growth rate are analyzed. Results show that in an electron–positron plasma with certain background density, the intensity of the modulation instability is mainly determined by the competition between the nonlinearity in the interaction and the relativistic light ponderomotive driven density responses.     

Darboux Transformation and Explicit Solutions for Discretized Modified Korteweg-de Vries Lattice Equation

The modified Korteweg-de Vries （mKdV） typed equations can be used to describe certain nonlinear phenomena in fluids, plasmas, and optics. In this paper, the discretized mKdV lattice equation is investigated. With the aid of symbolic computation, the discrete matrix spectral problem for that system is constructed. Darboux transformation for that system is established based on the resulting spectral problem. Explicit solutions are derived via the Darboux transformation. Structures of those solutions are shown graphically, which might be helpful to understand some physical processes in fluids, plasmas, and optics.     

Theory for explosive ideal magnetohydrodynamic instabilities in plasmas

Flux tubes confined in tokamaks are observed to erupt explosively in some plasma disruptions and edge localized modes. Similar eruptions occur in astrophysical plasmas, for example, in solar flares and magnetospheric substorms. A single unifying nonlinear evolution equation describing such behavior in both astrophysical and tokamak plasmas is derived. This theory predicts that flux tubes rise explosively, narrow, and twist to pass through overlying magnetic field lines without reconnection.     

Nonlinear Theory of the Instability of a Modulated Electron Beam of Low Density in a Plasma. V. Excitation of Waves in Strong Dissipative Plasmas by a Monoenergetic Beam

A system of nonlinear equations derived in a previous paper which describes the evolution of the beam-plasma instability in strong dissipative plasmas is solved numerically. It is shown that there are three characteristic solutions of the system of equations: the resonant dissipative instability, the nonresonant instability with strong dissipation and the nonresonant dissipative instability. A physical interpretation of essential features of these instabilities is given. The interaction of resonant and nonresonant waves in the system electron beam-strong dissipative plasma is examined. Some conclusions for the transport problem of electron beams in strong dissipative plasmas are obtained in this paper.