On coupled fields in stratified plasmas with tensor pressure perturbations — II

This paper deals with small-amplitude waves, described by Maxwell's equations and single-fluid hydrodynamics, in horizontally stratified, continuously varying plasmas with anisotropic electron pressure perturbations. A set of coupled wave equations in first-order matrix form, which describes two different types of obliquely propagating horizontally polarized transverse waves, is treated by the method of Clemmow and Heading. It is then transformed by Heading's method into a form which is valid throughout reflection regions, and from which a pair of second-order coupled wave equation in Fösterling's form follows.     

On coupled fields in warm stratified plasmas

This paper deals with small-amplitude coupled electromagnetic and electron acoustic waves, as described by Maxwell's equation and single-fluid hydrodynamics, in a horizontally stratified, continuously varying, warm electron plasma. First-order coupled wave equations are used to investigate the fields in a coupling region, and the results are compared with those obtained from second-order coupled wave equations. All field components are found to be finite in the coupling region.Nedlands, Western Australia, 6009.     

Singularities of coupled fields in warm stratified plasmas

This paper deals with waves, described by Maxwell's equations coupled to single-fluid hydrodynamic equations, in a warm continuously stratified electron plasma. The behaviour of the fields in a coupling region, excited by an incident electron-acoustic wave, is investigated.     

On coupled waves in stratified CGL-plasma

Starting from the Chew-Goldbsrger-Low equations we derive wave-equations describing small amplitude disturbances in a horizontally stratified, continuously varying CGL-plasma. A set of equations of first-order matrix form is treated by the method of Clemmow and Heading.     

Propagation and spreading of unstable perturbations in electron-hole plasmas subject to crossed fields

A model is developed for electrostatic drift instabilities which arise in inhomogeneous electron-hole plasmas subject to crossed fieldsE ₀B ₀. The instabilities are initiated by gradients in the equilibrium plasma densityn ₀. Using two-fluid magnetohydrodynamics and linear perturbation theory the dispersion relation of local density oscillations is calculated for arbitrary inhomogeneous equilibrium distributions and plasma densities. For cases wheren ₀B ₀ andn ₀ ⁺ n ₀ ^- it is found that the propagation direction of maximal gain, , is the bisectrix of the angle between (–n ₀) and (E ₀ ×B ₀) and that stable and unstable configurations are distinguished by the angle between ₀ andn ₀. A local density perturbation built by superpositions of the plane waves, and initially chosen radially symmetric, broadens unisotropically. In the direction transverse to the broadening is anomaleously enhanced, as compared to the broadening by diffusion in the stable case. The results are referred to experimental observations of low-frequency instabilities reported in [1].     

High-frequency perturbations of coupled gravitational and electromagnetic fields in a weakly ionized dust

Wavelike perturbations of a system consisting of a gravitational and an electromagnetic field and a dust with a small ionized component are studied. By using the spin coefficient formalism we expand the perturbations of the various quantities characterizing the system into asymptotic series. The whole dynamics of high-frequency waves is shown to be governed by four propagation equations for the expansion coefficients of the tetrad components and of perturbations of the Weyl tensor and Maxwell tensor in each order of the expansion. The perturbations of all the other variables can be derived without integration. The propagation equations are explicitly derived and discussed in the zeroth-order (geometrical optics) and in the first-order approximation. The influence of dust and plasma on the propagation is considered in the first-order equations.     

气压对微束射频容性放电模式调制的研究

微束射频容性放电在纳米晶体颗粒等离子体增强气相合成有着潜在的应用前景.本论文利用ICCD、单反相机、高压探头和电流探头等对微束射频容性放电特性进行了实验诊断研究.结果发现:在纯氩气微束射频放电中,随着气压的增加,放电从辉光放电模式向多通道丝状放电模式转换;在99％氩/1％氢混合气体微束射频放电中,丝状放电模式消失,而是...     

On Bianchi-I cosmic strings coupled with Maxwell fields in bimetric relativity

Axially symmetric Bianchi-I model is studied with source cosmic cloud strings coupled with electromagnetic field in Rosen’s bimetric theory of relativity and observed that there is no contribution from cosmic strings and Maxwell fields in this theory.     

Recalculation of the diffusion tensor for plasmas with ion-acoustic turbulence

The quasi-linear theory of a plasma with wave-particle collisions is reconsidered for the case of current-driven ion-acoustic turbulence. Especially the angular dependence of the energy spectrum of the waves is taken into account more accurately in the quasi-linear collision integral. The kinetic equation is solved assuming that the scales of the density gradients of the plasma parallel and perpendicular to an external magnetic field are much larger than the effective mean free path of the electrons. Expressions for the electron diffusion tensor are developed and estimates of the diffusion in solar flare plasmas are made.Published from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 2, pp. 148–162, February, 1996.     

Electronic dynamic behavior in inductively coupled plasmas with radio-frequency bias

The inflexion point of electron density and effective electron temperature curves versus radio-frequency （RF） bias voltage is observed in the H mode of inductively coupled plasmas （ICPs）. The electron energy probability function （EEPF） evolves first from a Maxwellian to a Druyvesteyn-like distribution, and then to a Maxwellian distribution again as the RF bias voltage increases. This can be explained by the interaction of two distinct bias-induced mechanisms, that is： bias- induced electron heating and bias-induced ion acceleration loss and the decrease of the effective discharge volume due to the sheath expansion. Furthermore, the trend of electron density is verified by a fluid model combined with a sheath module.     

Collective behavior in coupled chaotic map lattices with random perturbations

Numerical simulations of coupled map lattices with non-local interactions (i.e., the coupling of a given map occurs with all lattice sites) often involve a large computer time if the lattice size is too large. In order to study dynamical effects which depend on the lattice size we considered the use of small truncated lattices with random inputs at their boundaries chosen from a uniform probability distribution. This emulates a “thermal bath”, where deterministic degrees of freedom exhibiting chaotic behavior are replaced by random perturbations of finite amplitude. We demonstrate the usefulness of this idea to investigate the occurrence of completely synchronized chaotic states as the coupling parameters are varied. We considered one-dimensional lattices of chaotic logistic maps at outer crisis x→4x(1−x).     

The Biermann battery effect at the interfaces in stratified plasmas

The Biermann battery arises because an inhomogeneous electron pressure acts as a source term for the magnetic field. In order to better understand its effects, we consider a simplified model formed by the boundary between two fluids with different mean molecular weight and look for magnetic fields generated by the battery and localized in a band around the interface. We show that a parallel field is generated, which tends to push the original flow away from the boundary creating a rarefaction band. The specific forms of magnetic field and velocity are detailed.     

Interaction of microwaves with atmospheric pressure plasmas

In this paper, the interaction of microwaves with a plasma, generated at atmospheric pressure, is studied. The refractive index, attenuation index, skin depth, attenuation coefficient, phase coefficient, and reflectivity are investigated as functions of the plasma number density, the wave frequency and type of polarization, and the grazing angle. It is found that two frequency regimes characterize these type of plasmas. The first is a range where the phase velocity and attenuation of the wave both increase with frequency. The second is a frequency range in which the phase velocity and attenuation of the wave remain constant. It is also found that to have a shallow skin depth, the plasma number density has to be in the 10¹³ cm^–3 range. The reflectivity is found to be an increasing function of the number density. In horizontal polarization, the reflectivity is a decreasing function of the grazing angle. But in vertical polarization and for grazing angle less than 20°, the reflectivity has a maximum at a frequency , where f_pe is the electron plasma frequency and v is the collision frequency.     

Asymptotical solutions of coupled nonlinear Schrodinger equations with perturbations

In this paper Lou＇s direct perturbation method is applied to the perturbed coupled nonlinear Schrodinger equations to obtain their asymptotical solutions, which include not only the zero-order solutions but also the first-order modifications. Based on the asymptotical solutions, the effects of perturbations on soliton parameters and the collision between two solitons are then discussed in brief. Furthermore, we directly simulate the perturbed coupled nonlinear SchrSdinger equations by split-step Fourier method to check the validity of the direct perturbation method. It turns out that our analytical results are well supported by the numerical calculations.