Influence of Generalized (r, q) Distribution Function on Electrostatic Waves

Non-Maxwellian particle distribution functions possessing high energy tail and shoulder in the profile of distribution function considerably change the damping characteristics of the waves. In the present paper Landau damping of electron plasma (Langmuir) waves and ion-acoustic waves in a hot, isotropic, unmagnetized plasma is studied with the generalized (r,q) distribution function. The results show that for the Langmuir oscillations Landau damping becomes severe as the spectral index r or q reduces. However, for the ion-acoustic waves Landau damping is more sensitive to the ion temperature than the spectral indices.     

Nonlinearly-coupled Langmuir and Ion-Acoustic Waves

In a plasma acted on by an intense laser field, one encounters the problem of nonlinearly-coupled Langmuir and ion-acoustic waves. We use a generalized perturbation theory to discuss the nature of coupled oscillatory waves in this system, and the possibility of formation of an ionsheath.     

Parametric instabilities in single-walled carbon nanotubes

Parametric instabilities induced by the coupling excitation between the high frequency quantum Langmuir waves and the low frequency quantum ion-acoustic waves in single-walled carbon nanotubes are studied with a quantum Zakharov model. By linearizing the quantum hydrodynamic equations, we get the dispersion relations for the high frequency quantum Langmuir wave and the low frequency quantum ion-acoustic wave. Using two-time scale method, we obtain the quantum Zaharov model in the cylindrical coordinates. Decay instability and four-wave instability are discussed in detail. It is shown that the carbon nanotube＇s radius, the equilibrium discrete azimuthal quantum number, the perturbed discrete azimuthal quantum number, and the quantum parameter all play a crucial role in the instabilities.     

Interaction of ion-acoustic solitons with Langmuir turbulence

The interaction of ion-acoustic solitons with Langmuir waves has been considered. Investigation was performed in the approximation of a slow change in soliton parameters compared with the time of evolution of wave spectrum. This permitted a two-stage solution of the problem. First the Langmuir wave spectrum changes in the given field of a soliton were found. Then the action of high-frequency waves on the soliton was taken into account.     

Cavitating Langmuir turbulence in the terrestrial aurora

Langmuir cavitons have been artificially produced in Earth's ionosphere, but evidence of naturally occurring cavitation has been elusive. By measuring and modeling the spectra of electrostatic plasma modes, we show that natural cavitating, or strong, Langmuir turbulence does occur in the ionosphere, via a process in which a beam of auroral electrons drives Langmuir waves, which in turn produce cascading Langmuir and ion-acoustic excitations and cavitating Langmuir turbulence. The data presented here are the first direct evidence of cavitating Langmuir turbulence occurring naturally in any space or astrophysical plasma.     

Parametric instabilities in quantum plasmas with electron exchange-correlation effects

Parametric instabilities induced by the nonlinear interaction between high frequency quantum Langmuir waves and low frequency quantum ion-acoustic waves in quantum plasmas with the electron exchange-correlation effects are presented.By using the quantum hydrodynamic equations with the electron exchange-correlation correction,we obtain an effective quantum Zaharov model,which is then used to derive the modified dispersion relations and the growth rates of the decay and four-wave instabilities.The influences of the electron exchange-correlation effects and the quantum effects on the existence of quantum Langmuir waves and the parametric instabilities are discussed in detail.It is shown that the electron exchange-correlation effects and quantum effects are strongly coupled.The quantum Langmuir wave can propagate in quantum plasmas only when the electron exchange-correlation effects and the quantum effects satisfy a certain condition.The electron exchange-correlation effects tend to enhance the parametric instabilities,while quantum effects suppress the instabilities.     

不均匀等离子体中电磁波与Langmuir波的相互作用

通过理论研究与数值计算,不均匀等离子体中Langmuir波与电磁波的相互作用及其线性模式转换规律得到了充分的展示.导出了不均匀等离子体中的电磁色散关系,研究了入射电磁波或Langmuir波在通过不均匀等离子体的过程中发生转换的物理过程,以及波的传播矢量随空间坐标变化的关系,并对电磁波与Langmuir波相互作用的机理进行了讨论.研究结果对密度梯度所驱动的等离子体波产生电磁辐射的研究具有重要意义. 关键词： 电磁波 Langmuir波 不均匀等离子体 线性模式转换     

Complex impedance of nonisotermic plasma capacitor

The capacitance of a planar capacitor filled with nonisothermic collisional plasma was calculated in the hydrodynamic approximation. Resonant properties of the complex impedance of the capacitor were studied. It was shown that resonant absorption in the capacitor is caused by excitation of ion-acoustic oscillations, the excitation of electron Langmuir waves, and the geometric plasma resonance phenomenon in the low-, high-, and intermediate frequency regions, respectively.     

A unified theory of nonlinear Langmuir waves, ion-acousticsolitons, and double layers

Steady-state, nonlinear potential solutions in a two-fluid plasma are formulated in terms of an integral equation that expresses the conservation of total pressure. By appropriately specifying the conservation constants and boundary conditions of the effective potential function, the integral curves yield, respectively, three types of solutions: nonlinear Langmuir waves, ion-acoustic solitons, and double layers. The similarities and differences of the existence conditions for these nonlinear potential structures are discussed     

Effect of the anisotropy of a conducting layer on the dispersion law of electromagnetic waves in layered metal-dielectric structures

The dispersion laws of electromagnetic waves in layered periodic metal-dielectric structures with anisotropic metal layers have been theoretically analyzed. It has been found that the anisotropy of metal layers is responsible for the appearance of additional allowed energy bands for photons. It has been shown that these bands correspond to plasma (Langmuir) waves propagating in anisotropic metal layers of the structure. Conditions under which the directions of group and phase velocities of Langmuir waves coincide or are opposite have been determined. It has been shown that the penetration of the electromagnetic field of Langmuir waves into dielectric layers is exponentially weak and this field is primarily concentrated in metal layers, where it oscillates in the direction perpendicular to the plane of the layers.     

Stimulated Brillouin effect in weakly ionized plasma

The stimulated Brillouin effect in gaseous plasma is investigated by means of classical coupledmode analysis. This process is described as interaction between an ion-acoustic plasma wave and two light waves. The threshold power levels calculated are achievable in giant-pulse lasers. However, the Brillouin effect may possibly be observable in the dense plasma or in the far infrared region of the electromagnetic spectrum.     

Bright,periodic, compacton and bell-shape soliton solutions of the extended QZK and (3+1)-dimensional ZK equations

The(3+1)-dimensional Zakharov–Kuznetsov(ZK) and the new extended quantum ZK equations are functional to decipher the dense quantum plasma, ion-acoustic waves, electron thermal energy,ion plasma, quantum acoustic waves, and quantum Langmuir waves. The enhanced modified simple equation(EMSE) method is a substantial approach to determine competent solutions and in this article, we have constructed standard, illustrative, rich structured and further comprehensive soliton solutions via this method. The solutions are ascertained as the integration of exponential, hyperbolic,trigonometric and rational functions and formulate the bright solitons, periodic, compacton, bellshape, parabolic shape, singular periodic, plane shape and some new type of solitons. It is worth noting that the wave profile varies as the physical and subsidiary parameters change. The standard and advanced soliton solutions may be useful to assist in describing the physical phenomena previously mentioned. To open out the inward structure of the tangible incidents, we have portrayed the three-dimensional, contour plot, and two-dimensional graphs for different parametric values. The attained results demonstrate the EMSE technique for extracting soliton solutions to nonlinear evolution equations is efficient, compatible and reliable in nonlinear science and engineering.     

A Pair of Zakharov Equations with Collisional Damping and the Motion of Langmuir Soliton

The effects of collisional damping on high frequency Langmuir wave and low frequency ion-acoustic wave have been investigated. It is found that the governing equations for the waves are a pair of Zakharov equations with a damping term in each equation. By using the treatment which consists of approximate solutions of the balance equations, a set of first order ordinary differential equations have been derived for the solution parameters in order to study the motion of Zakharov solitons in presence of damping. It has been shown that the width of the soliton remains constant throughout the motion.     

Nanolayer parametric instability in near-field optics

Parametric decay of electromagnetic waves into two Langmuir oscillations near the quarter critical density is suggested as being attributable to an enhanced electric field and to surface-enhanced Raman scattering in near-field optics. A nanolayer of silver aggregates localizes the wave in the evanescent region to a one-wavelength span and results in a wave-number mismatch as well as in a reduced growth rate. The fastest-growing mode has a growth rate that scales with the square root of the nanolayer's thickness.     

High-frequency emissions during the propagation of an electron beamin high-density plasma

A relativistic annular electron beam passing through a high-density plasma excites Langmuir waves via Cerenkov interaction. The Langmuir waves are backscattered off ions via nonlinear ion Landau damping. At moderately high amplitudes these waves are parametrically up-converted by the beam into high-frequency electromagnetic radiation, as observed in some recent experiments. A nonlocal theory of this process is developed in a cylindrical geometry. It is seen that the growth rate of the Langmuir wave scales as one-third the power of beam density. The growth rate of parametric instability scales as one-fourth the power of beam density and the square root of beam thickness     

Electrodynamics and dispersion properties of a magnetoplasma containing elongated and rotating dust grains

The electrodynamics and dispersion properties of a magnetized dusty plasma containing elongated and rotating charged dust grains are examined. Starting from an appropriate Lagrangian for dust grains, a kinetic equation for the dust grain and the corresponding equations of motion are derived. Expressions for the dust charge and dust current densities are obtained with the finite size (the dipole moment) of elongated and rotating dust grains taken into account. These charge and current densities are combined with the Maxwell-Vlasov system of equations to derive dispersion relations for the electromagnetic and electrostatic waves in a dusty magnetoplasma. The dispersion relations are analyzed to demonstrate that the dust grain rotation introduces new classes of instabilities involving various low-frequency waves in a dusty magnetoplasma. Examples of various unstable low-frequency waves include the electron whistler, the dust whistler, dust cyclotron waves, AlfvÉn waves, electromagnetic ion-cyclotron waves, as well as lower-hybrid, electrostatic ion cyclotron, modified dust ion-acoustic waves, etc. Also found is a new type of unstable waves whose frequency is close to the dust grain rotation frequency. The present results should be useful in understanding the properties of low-frequency waves in cosmic and laboratory plasmas that are embedded in an external magnetic field and contain elongated and rotating charged dust grains.     

Can ion-acoustic waves in plasma be backward waves?

The dispersion relation for ion-acoustic waves in plasma with ion flow has been analyzed. It is shown that these waves may exist (under certain conditions) in the form of backward waves with antiparallel group and phase velocities. The range of ion flow velocities allowing implementation of backward ion-acoustic waves is found.     

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.     

The effect of trapped electrons on large amplitude ion-acousticwaves in a plasma with an electron beam

The nonlinear wave structures of large amplitude ion-acoustic waves are investigated in an electron beam-plasma system with trapped electrons, by the pseudopotential method. The speed of the ion-acoustic wave increases as the effect of trapped electrons decreases and the beam temperature increases. The region of the existence of ion-acoustic waves is examined, showing that the condition of the existence sensitively depends on the parameters such as the effects of the electron beam density and temperature, electrostatic potential, and the effect of trapped electrons. It turns out that the region of existence spreads as the effect of trapped electrons decreases and beam temperature increases. New findings of large amplitude ion-acoustic waves in an electron beam-plasma system with trapped electrons are predicted     

Van Kampen and Case Formalism Applied to Linear and Weakly Nonlinear Initial Value Problems in Unmagnetized Plasma

A unified account is given of the normal mode theory of homogeneous unmagnetized plasma. Electron (Langmuir), ion sound and electromagnetic waves are treated in stable and (Penrose) unstable plasma with the Van Kampen-Case formalism, using generalized functions. Simplified formulae are derived for second-order Langmuir waves, taking full account of free-streaming effects.