Semi-infinite Plasma Research Articles

Effect of magnetic resistivity on the stability of a partially ionized compressible Hall plasma

The dynamic stability of a partially ionized, compressible Hall plasma of finite electrical conductivity has been investigated when the plasma is immersed in a uniform, horizontal magnetic field. Based on the variational principle, which is shown to characterize the problem, the solution has been obtained for a semi-infinite plasma confined between two planes and having an exponential density stratification along the vertical. It is found that the effect of neutral gas friction is stabilizing while magnetic resistivity, Hall currents and compressibility all have destabilizing influence.

Stability of a Rotating Compressible Stratified Plasma in the Presence of Hall Currents and Magnetic Resistivity

AbstractThe dynamic instability in a horizontal layer of a rotaing compressible plasma of variable density has been investigated to examine the influence of the simultaneous presence of the effects of Hall currents and finite magnetic resistivity. The linearized stability analysis has been carried out through the normal mode technique. By making use of the existence of a variational principle which is shown to characterize the problem, proper solutions have been obtained for a semiinfinite plasma in which there is an exponential density gradient along the vertical. The dispersion relation obtained has been solved numerically and it is found that both the resistivity and the Hall currents have a destabilizing influence as the growth rate of the unstable disturbances increases with increasing values of the parameters characterizing these effects. On the other hand, the Coriolis forces are found to have a stabilizing influence for in this case the growth rate decreases with increasing rotation.

Current responses of first and second order in a collisionless plasma. IV. Applications

The purpose of this paper is to illustrate with a few concrete examples how the general formulas given in the preceding papers I–III may be used. We consider three different background plasmas: a homogeneous static magnetized plasma, a homogeneous magnetized plasma in an oscillating electric field, and a semi-infinite homogeneous static magnetized plasma. The coupled mode equations governing resonant three-wave interaction are given in each case.

Comment on ‘‘Electromagnetic decay into a surface plasma wave and an ion acoustic surface wave in a semi-infinite plasma’’

It is pointed out that the parametric instability of surface modes in a semi-infinite plasma is a four-wave process and the threshold should be ∼0.7(mi/me)1/2 times larger than that found by Yasumoto [J. Appl. Phys. 52, 3238 (1981)].

Nonlinear interaction of waves in sharply bounded plasmas

We consider the nonlinear interaction of three high-frequency waves and lowfrequency density perturbations in a sharply bounded plasma. The coupled equations are presented in a general and convenient form. To demonstrate the usefulness of our method we derive explicit expressions for the threshold of a number of possible instabilities in semi-infinite and cylindrical plasmas.

Effects of gyroviscosity and hall currents on the stability of a stratified rotating self-gravitating plasma

Instability in a horizontal layer of a stratified rotating self-gravitating plasma is studied to include simultaneously the effects of Hall currents and the finiteness of the ion Larmor radius. Proper solutions have been obtained through the variational methods for a semi-infinite plasma in which the density has an exponential gradient along the vertical. The dispersion relation obtained has been solved numerically and it is found that the growth rate of the unstable perturbations decreases with both coriolis forces and gyroviscous effects. The influence of the effects of gyroviscosity as well as of Coriolis forces is consequently stabilizing. Hall currents are found to have a destabilizing influence as the growth rate is found to increase with this effect.

Material and electromagnetic energy flows generated in a spatially dispersive solid-state plasma by an electromagnetic wave impinging upon the surface at oblique incidence

The anisotropic conductivity of a semi-infinite free-electron solid-state plasma having a sharp boundary is calculated assuming specular electron surface scattering. Explicit expressions for the conductivity-tensor components are presented for a fully degenerate plasma with special emphasis on the near-local regime. With the assumption that the monochromatic electromagnetic plane wave penetrates the surface at an oblique angle, the reflected and transmitted fields are determined. By combining Maxwell's equations and the nonlinear Boltzmann equation the energy transport in the plasma is studied. With spatial dispersion effects taken into account, the cycle-averaged Poynting vectors of the plasma, originating in the induced dc mass transport of the conduction electrons, and of the electromagnetic field are determined. A particular investigation is devoted to the case of TE-mode propagation in the near-local regime, with emphasis on (i) a discussion of the angular deviation of the plasma Poynting vector from the electromagnetic Poynting vector and (ii) a calculation of the ratio between the magnitudes of the energy flows. The ''problem'' of the violation of the principle of energy conservation at a sharp boundary is considered.

Solitary surface waves

By means of the cold electron plasma equations, we have shown that surface soliton solutions can exist in semi-infinite plasmas.

Surface instability of a current carrying plasma under the influence of a high frequency electric field

Surface instability of a collisionless semi-infinite current carrying plasma is studied. The semi-infinite plasma bounded by a plane surface is under the influence of a high frequency (hf) field. There are two classes of surface modes. One is a normal extension of zero high frequency field and the other due entirely to the presence ofhf field. As expected, with the increase in thehf field, the growth rates of the surface instabilities decrease. There are regions defined by the electron drift velocityu where the unstable surface and bulk regions overlap. The interesting result is that unlike the bulk plasma, there is a stable region on theu-axis flanked by two unstable regions. The width of this stable region increases with the increase in the field strength.

Electromagnetic decay into two surface plasma waves in a semi-infinite plasma

The parametric decay instability of two high-frequency surface plasma waves, which arises when an intense electromagnetic plane wave is incident on a semi-infinite, unmagnetized plasma from a vacuum, is investigated on the basis of the hydrodynamic equations for warm electrons. It is shown that the instability occurs only if the incident wave is of the transverse magnetic type. The growth rate for the instability and the threshold amplitude of the incident wave are determined. In contrast to the usual ’’two-plasmons decay instability’’ in an infinite, unmagnetized plasma, the present ’’surface-decay instability’’ is possible even if the incident pump field is spatially homogeneous.

Nonlinear interaction of electrostatic surface waves in a semi-infinite plasma. Part 2. Time-dependent solutions to the coupled mode equations

The coupled mode equations which govern the nonlinear interaction of three electrostatic high-frequency surface waves and a low-frequency density perturbation are analysed considering time-dependent solutions only. We show the existence of a filamentation instability in the static limit for the low-frequency density perturbation. In the opposite case (density perturbation close to the lowfrequency surface wave resonance) we arrive at a decay instability where only surface waves take part. The parametric approximation (growth rate and threshold) as well as the nonlinear evolution of both types of instabilities are studied.

Nonlinear interaction of electrostatic surface waves in a semi-infinite plasma. Part 1. Derivation of the coupled mode equations

We have derived a set of coupled mode equations which govern the nonlinear interaction of three high-frequency electrostatic surface waves through a low-frequency density perturbation produced by them. The set is compared with that obtained when a similar problem is solved for bulk waves in an infinite plasma. Some differences are shown to exist caused by the specific features of surface waves such as the amplitude attenuation normal to the interface and their hybrid nature.

Electrodynamics of Plasma with Random Scattering Boundary

The general electromagnetic solution of the set of Maxwell-Boltzman equations is obtained for the case of semi-infinite multicomponent plasma at the assumption that (i) the random scattering of charged particles at the boundary takes place and (ii) the full particle flow is convserved in the process of scattering. The dielectric response function and the correlation functions for microcurrents have been found for such a plasma system and the relation between these functions has been written in the form of a generalization of the fluctuation-dissipation theorem. As the applications of these results to the investigation of physical phenomena the reflection of a plane wave from the plasma-dielectric interface and the spectrum of excitations in a plasma with random scattering boundary were considered.

On the surface properties of a semi-infinite classical plasma model with permeable boundary

We discuss the surface density profile and other surface properties of a classical plasma on a semi-infinite neutralizing background with a permeable boundary. The asymptotic behaviours of the charge density profile can be determined exactly to be of inverse-square-power form outside the boundary and of exponential form, with a switch-over to a damped oscillatory behaviour above a eritical value for the strength of the interactions, inside the boundary. In a local approximation for the free-energy density, instead, a regular solution for the profile has a monotonic behaviour and exists only over a finite range for the strength of the interactions once the known features of the equation of state of the homogeneous plasma are incorporated. Local approximations of increasing sophistication, starting from the simplest Debye-Hückel approximation, are then evaluated and their results compared.

Dispersion and energy conservation relations of surface waves in semi-infinite plasma

The hydrodynamic theory of surface wave propagation in semi-infinite homogeneous isotropic plasma is considered. Explicit linear surface wave solutions are given for the electric and magnetic fields, charge and current densities. These solutions are used to obtain the well-known dispersion relations and, together with the general energy conservation equation, to find appropriate definitions for the energy and the energy flow densities of surface waves. These densities are associated with the dispersion relation and the group velocity by formulae similar to those for bulk waves in infinite plasmas. Both cases of high-frequency (HF) and low-frequency (LF) surface waves are considered.

Surface wave instability in bounded magnetized plasma with inhomogeneous particle stream

The instability of surface wave modes in a semi infinite magnetoactive plasma with a non-homogeneous particle stream is studied. The existence of two possible mechanisms for the development of the instability: induced anomalous Doppler effect and induced Cherenkov effect is demonstrated. Related growth-rates and stability criteria are calculated.

Scattering of electromagnetic waves by proper waves in a semiinfinite plasma

Scattering of electromagnetic waves by proper waves in a semiinfinite plasma

Structure of the electric field of low-frequency surface waves in a semi-infinite plasma

The wave electric field attenuation of the low-frequency surface waves normally to the plasma-vacuum interface has been investigated. It is shown that the field of ion acoustic surface waves attenuates weakly while in the short-wavelength limit the wave field is concentrated at a distance of the order of one wavelength. The applicability both of kinetic and hydrodynamic treatment of the problem is discussed.

Surface waves in a homogeneous plasma sharply bounded by a dielectric

The physics, spectra and damping rates of high- and low-frequency surface waves in semi-infinite and cylindrical plasmas are studied. The boundary conditions (both macroscopic and microscopic) imposed on the plasma fluid/particles are discussed. The solution of the Vlasov-Maxwell set of equations for semi-infinite and cylindrical plasmas assuming mirror reflection of plasma particles at the boundary is given. The dispersion relations are derived and analysed. The dispersion properties obtained from the kinetic model are compared with those derived from the fluid model.

Enhanced Fluctuations in Semi-infinite Plasmas

We consider a semi-infinite plasma in the presence of a uniform, externally applied, high-frequency electric field. By means of kinetic theory we obtain the radiation spectrum and the spectral density of the space charge correlations. The dispersion relations, describing the parametric excitation of both volume and surface waves, are obtained. The possibility of anomalous growth of the radiation intensity and of the fluctuation level is discussed.