Absolute parametric instability in a nonuniform plane plasma waveguide

The paper reports an analysis of the effect of spatial plasma nonuniformity on absolute parametric instability (API) of electrostatic waves in magnetized plane waveguides subjected to an intense high-frequency (HF) electric field using the separation method. In this case the effect of strong static magnetic field is considered. The problem of strong magnetic field is solved in 1D nonuniform plane plasma waveguide. The equation describing the spatial part of the electric potential is obtained. Also, the growth rates and conditions of the parametric instability for periodic and aperiodic cases are obtained. It is found that the spatial nonuniformity of the plasma exerts a stabilizing effect on the API. It is shown that the growth rates of periodic and aperiodic API in nonuniform plasma are less compared to that of uniform plasma.     

Modulational instability of ion—acoustic waves in a warm plasma

Using the standard reductive perturbation technique,a nonlinear Schroedinger equation is derived to study the modulational instability of finite-amplitude ion-acoustic waves in a non-magnetized warm plasma.It is found that the inclusion of ion temperature in the equation modifies the nature of the ion-acoustic wave stability and the soliton stuctures.The effects of ion plasma temperature on the modulational stability and ion-acoustic wave properties are inestigated in detail.     

Multi-dimensional instability of electrostatic solitary waves in a warm multi-ion dust plasma

Study of dust ion acoustic waves in a magnetized dusty plasmas composed of negatively or positively charged static dust, positive and negative ions, as well as kappa distribution electrons is presented. The Zakharov–Kuznetsov (ZK) equation is derived via reductive perturbation technique. The solitary wave solution of ZK equation is given and the multi-dimensional instability of these solitary waves is investigated via small k perturbation method. The instability criterion and growth rate relying on obliqueness, superthermality, positive ion thermal pressure, relative ion number density, magnetic field strength, and direction cosines are discussed for five cases. The results are beneficial to understand different nonlinear characteristics of unstable electrostatic disturbances in laboratory and space plasmas.     

Absolute parametric instability in a turbulent,inhomogeneous medium

It is shown analytically that the convective saturation of parametric instabilities in an infinite inhomogeneous medium can disappear in the presence of background turbulence. Absolute instability then occurs.     

Threshold of ion cyclotron parametric instability in a multispecies plasma

Experimental and theoretical studies are presented of ion cyclotron parametric instability into two electrostatic ion cyclotron waves in a multispecies plasma. The instability threshold obtained experimentally is in reasonable agreement with that predicted theoretically.     

Interaction of electromagnetic waves with a magnetized nonuniform plasma slab

The absorption, reflection, and transmission of electromagnetic waves by a nonuniform plasma slab immersed in an ambient uniform magnetic field of various strengths are studied in this paper. The effects of the plasma parameters and magnetic field strength on the absorbed, reflected, and transmitted power are discussed. The magnetized nonuniform plasma slab is modeled by a series of magnetized uniform plasma subslabs. The calculation results show that the effects of the magnetic field strength and density gradient on the absorbed power, as well as the frequency band of resonant absorption, are significant. A complete analysis utilizing the scattering matrix method is also used to compare the above calculation results which neglect multiple reflections between subslab interfaces. Broadband absorption of electromagnetic waves can be achieved by changing the magnetic field strength and plasma density. More than 90% of the electromagnetic wave power can be absorbed in a magnetized nonuniform plasma slab with width of 12 cm and the absorption bandwidth can range from 1 to 20 GHz with different plasma parameters and external magnetic field strengths.     

Concerning the electromagnetic instability of a homogeneous anisotropic plasma

A study is made of the electromagnetic instability of a homogeneous plasma with a highly anisotropic one-or two-dimensional velocity distribution in the absence of a magnetic field. It is shown that, if the velocity distribution has a center of symmetry, then the plasma is always unstable against sufficiently long electromagnetic waves. This instability plays an important role in both laboratory plasma devices and cosmic rays.     

Modulation instability of ion-acoustic waves in a multi-ion plasma

A nonlinear Schrödinger equation for ion-acoustic waves in a collision-free plasma, consisting of a mixture of two cold ion species and hot isothermal electrons is derived using the KBM method. It is used to discuss the modulation instability in which the effect of the light-on concentration is analysed. We find that the unstable region depends sensitively upon the fraction of light-ion concentration (α) and the ion-mass ratio. An approximate relation for α_critical is derived for a given ion species in terms of the ion-mass ratio, which governs the minimum wave number, below which the carrier wave is stable against the modulational instability.     

On the instability of electrostatic waves in a nonuniform electron–positron magnetoplasma

The dispersion properties of three-dimensional electrostatic waves in a nonuniform electron–positron (EP) magnetoplasma are analyzed. A new dispersion relation is derived by use of the electron and positron density responses arising from the electron and positron continuity and Poisson equations. In the local approximation, the dispersion relation admits two wave modes with different velocities. The growth rates of various modes are illustrated both analytically and numerically. Considering the temperature gradients produces a linearly stable transverse mode. The growth rate of the slow mode instability due to the density inhomogeneity only is the highest one, though it appears at higher thermal energy. The angle of the wave propagation affects drastically on the instability features in each case. The applications of the present analysis are briefly discussed.     

Generation of plasma waves by electron streams in a nonuniform solar corona

The one-dimensional process of propagation of a spatially bounded electron stream in the solar corona is simulated. It is shown that the background plasma inhomogeneity has a significant influence on the stream propagation and plasma-wave generation. The results are qualitatively interpreted in application to type III solar radio bursts, and model dynamic spectra of such bursts are constructed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 9, pp. 731–743, September 2006.     

Self-action of electromagnetic wave in plasma under parametric instability

The self-action of a strong electromagnetic wave in an inhomogeneous plasma is considered near the plasma resonance.     

Single-mode nonlinear regime of Weibel instability in a plasma with anisotropic temperature

An analytical solution is found to the vortex electron anisotropic hydrodynamic equations that describe the nonlinear evolution of the long-wavelength Weibel instability. The presented analytical approach shows that the long-wavelength Weibel instability saturates without a decrease in the temperature anisotropy in the single-mode regime due to the rotation of the anisotropy axes. The generated magnetic field is circular-polarized, and its amplitude varies periodically in time.     

Excitation of plasma waves by an externally applied electromagnetic wave to a nonuniform classical plasma

Radiation-driven plasma wave equations (RWE's) are derived from the basic dynamical plasma equations through restaining the external radiation source terms and significant nonlinear terms under the simplified assumptions used by Zakharov [1]. Excitation processes of the transverse plasma waves, Langmuir waves by an externally applied electromagnetic wave to a nonuniform unmagnetized plasma are investigated by means of rough numerical simulations based on RWE's. The results show that the amplitude of the transverse plasma waves is sensitive to their effective damping rate and that the radiation-induced density profile modification looks like a step, which are in qualitative agreement with analytical results.Published in Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 8, pp. 959–987, August, 1996.One of the authors (Li) wishes to thank V.L. Ginzburg, E. Mjølhus, B. Thidé, N.S. Erokhin, J.Y. Liu, J.W. Lee, T.D. Carozzi, and J. Bergman for helpful oral discussions on this topic. Li also wants to thank M. Matsuoka for the kind hospitality during his year-long stay at RIKEN, where this work was completed.     

Nonlinear interaction of compressional waves in a 2D dusty plasma crystal

Nonlinear mixing and harmonic generation of compressional waves were studied in a 2D Yukawa (screened Coulomb) triangular lattice. The lattice was a monolayer of highly charged polymer microspheres levitated in a plasma sheath. Two sinusoidal waves with different frequencies were excited in the lattice by pushing the particles with modulated Ar+ laser beams. Waves at the sum and difference frequencies and harmonics were observed propagating in the lattice. Phonons interacted nonlinearly only above an excitation-power threshold due to frictional damping, as predicted by theory.