Linear and Nonlinear Coupling of Electrostatic Drift and Acoustic Perturbations in a Nonuniform Bi-Ion Plasma with Non-Maxwellian Electrons

Linear and nonlinear coupling of drift and ion acoustic waves are studied in a nonuniform magnetized plasma comprising of Oxygen and Hydrogen ions with nonthermal distribution of electrons. It has been observed that different ratios of ion number densities and kappa and Cairns distributed electrons significantly modify the linear dispersion characteristics of coupled drift-ion acoustic waves. In the nonlinear regime, KdV (for pure drift waves) and KP (for coupled drift-ion acoustic waves) like equations have been derived to study the nonlinear evolution of drift solitary waves in one and two dimensions. The dependence of drift solitary structures on different ratios of ion number densities and nonthermal distribution of electrons has also been explored in detail. It has been found that the ratio of the diamagnetic drift velocity to the velocity of the nonlinear structure determines the existence regimes for the drift solitary waves. The present investigation may be beneficial to understand the formation of solitons in the ionospheric F-region.     

Dispersion and instability of electromagnetic waves in layered periodic semiconductor structures

The effect of carrier drift on the dispersive properties and instability of electromagnetic waves and plasma polaritons in infinite layered periodic semiconductors are considered. It is assumed that in similar semiconductor layers, carriers drift parallel to the interfaces. Drift waves are shown to have a specific band structure of the spectrum. The dispersive properties of collective plasma polaritons under drift are considered, the instability of the polaritons and drift waves is studied, and the instability increments are determined.     

Collisionless Drift Waves Ranging from Current‐Driven,Shear‐Modified,and Electron‐Temperature‐Gradient Modes

The specific history of collisionless drift waves is marked by focusing upon current‐driven, shear‐modified, and electron‐temperature‐gradient modes. Studies of current‐driven collisionless drift waves started in 1977 using the Innsbruck Q machine and was continued over 30 years until 2009 with topics such as plasma heating by drift waves in fusion‐oriented confinement and space/astrophysical plasmas. Superposition of perpendicular flow velocity shear on parallel shear intensively modifies the drift wave characteristics through the variation of its azimuthal structure, where the parallel‐shear driven instability is suppressed for strong perpendicular shears, while hybrid‐ion velocity shear cause unexpected stabilization of the parallel‐shear‐modified drift wave. An electron temperature gradient can be formed easily by control of thermionic electron superimposed on ECR plasma, and is found to excite low‐frequency fluctuation in the range of drift waves (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Linear and Nonlinear Magnetic Electron Drift Waves in a Nonuniform Strong Magnetic Field

Linear and nonlinear propagation of magnetic electron drift vortex waves in a nonuniform magnetic field is investigated by means of a generalized adiabatic law which takes into account the effect of strong fields and reduces in the appropriate limits to several well known energy conservation equations in a collisionless plasma. In the linear limit, an instability is shown to exist, whereas in the nonlinear regime, steady-state dipole vortices associated with the electron drift vortex waves may appear. The anomalous electron energy transport associated with the unstable magnetic electron drift vortex waves is investigated by means of a quasilinear theory.     

Particle drift in a resonance tube--a numerical study

The paper considers longitudinal drift of small particles in a resonance tube, caused by periodic shock waves, and its effect on particle agglomeration. It is found that depending on particle size, drift is caused by shock waves and/or gas acceleration and compression. It is also shown that the drift velocity and direction can be controlled by the frequency of the piston that causes gas oscillations in the resonance tube. The obtained numerical solutions indicate that particle drift in a resonance tube enhances aerosol agglomeration. An agglomeration kernel is derived for this case, accounting for particle drift, leading to an estimate of agglomeration time. The time predicted by present model is of the same order of magnitude as that obtained from experiments in the literature.     

Nonlinear interactions between drift waves and zonal flows

Phase coherent interactions between drift waves and zonal flows are considered. For this purpose, mode coupling equations are derived by using a two-fluid model and the guiding center drifts. The equations are then Fourier analyzed to deduce the nonlinear dispersion relations. The latter depict the excitation of zonal flows due to the ponderomotive forces of drift waves. The flute-like zonal flows with insignificant density fluctuations have faster growth rates than those which have a finite wavelength along the magnetic field direction. The relevance of our investigation to drift wave driven zonal flows in computer simulations and laboratory plasmas is discussed. Received 5 April 2002 Published online 28 June 2002     

The experimental determination of fluctuation line profiles in a weakly turbulent plasma

In a weakly turbulent plasma, the frequencies of fluctuations approximate to those determined by linear instability theory but with a significant spread. We determine the line profiles for drift waves in quadrupole geometry, showing that while they sometimes confirm to the expected lorentzian shape, profiles of gaussian shape are also observed; however, it is not yet certain that these are intrinsic to the drift waves rather than deriving from external random perturbations.     

A new spiky soliton and an explosive mode of the nonlinear driftwave equation

A new type of nonlinear wave modes which occurs in the electrostatic drift waves in an inhomogeneous magnetized plasma is presented. The author predicts the existence of a new type of spiky solitary wave and an explosive mode with a negative potential as stationary solutions of this equation. These solutions are a consequence of a density gradient and not connected with a temperature gradient. These new nonlinear wave solutions appear to make a step forward in the general scheme of nonlinear normal modes for plasma waves. Using these nonlinear wave modes, the author can explain the solitary structure and the explosive event concerning nonlinear drift waves propagating in space     

Sheared Flow Driven Drift Instability and Vortices in Dusty Plasmas with Opposite Polarity

Low-frequency electrostatic drift waves are studied in an inhomogeneous dust magnetoplasma containing dust with components of opposite polarity. The drift waves are driven by the magnetic-field-aligned (parallel) sheared flows in the presence of electrons and ions. Due to sheared flow in the linear regime, the electrostatic dust drift waves become unstable. The conditions of mode instability, with the effects of dust streaming and opposite polarity, are studied. These are excited modes which gain large amplitudes and exhibit interactions among themselves. The interaction is governed by the Hasegawa-Mima (HM) nonlinear equation with vector nonlinearity. The stationary solutions of the HM equation in the form of a vortex chain and a dipolar vortex, including effects of dust polarity and electron (ion) temperatures, are studied. The relevance of the present work to space and laboratory four component dusty plasmas is noted.     

Rectification of space-charge waves upon optical and electrical excitation

A comparative analysis is performed for three optical and electrical methods of exciting space-charge waves in photosemiconductors: (i) excitation by an external ac electric field combined with a static interference pattern, (ii) excitation by a moving interference grating, and (iii) excitation by an oscillating interference grating. It is shown that, in the case when space-charge waves are excited using a combination of all three methods, the dependence of the direct current passing through a sample on the excitation frequency exhibits two peaks that correspond to the resonant excitation of two modes of space-charge oscillations, namely, drift waves and trap recharging waves. It is noted that experimental observation of the peak attributed to the excitation of trap recharging waves should not pose any problems, whereas observation of the second peak associated with the excitation of drift waves is significantly complicated because of the small magnitude of the effect, especially for materials with a low electrical conductivity (or a long Maxwell relaxation time).     

Scattering of electromagnetic waves by drift modes

It is shown that high-frequency electromagnetic waves can parametrically excite the convection and ion drift waves in a slightly inhomogeneous magnetized plasma. The growth rates of the nonlinear decay instabilities are obtained analytically.     

Impact of electron exchange-correlation on drift acoustic solitary waves

The impact of electron exchange-correlation term on the linear and nonlinear quantum ion (QIA) acoustic drift waves in a highly degenerate plasma is investigated. An analytical approach is employed to derive the differential equation which is later on turned into Sagdeev energy integral equation that can be utilized to get drift solitons under existence conditions. It is noted that phase speed/frequency of the linear drift quantum ion acoustic (QIA) waves increases with electron exchange-correlation effect, but the amplitude of the corresponding solitons decreases with inclusion of these effects. Present study is carried out with reference to highly dense plasma environments like fast ignition inertial confinement fusion and white dwarfs etc.     

Waves in thin semiconductor layers with negative differential conductivity

Conclusion The wave process in semiconductor films with negative differential resistivity is peculiar in that there is a spatial increase of wave amplitude given the condition that the propagating wave has an electric field component along the direction of carrier drift. Such a condition is realized in structures with longitudinal drift when quasistatic space charge waves are amplified, and in structures with transverse drift, where quasiturbulent electromagnetic waves are amplified.In structures with longitudinal drift all propagating modes have identical phase velocity, close to the charge carrier drift velocity. The modes differ from each other in attenuation (amplification) coefficient and potential and charge distribution over film thickness. In structures with transverse drift only the fundamental quasi-TEM type mode is propagated, with a phase velocity close to the speed of light in the medium. Higher modes are nonpropagating due to cutoff of the waveguide structure.Experimental studies have confirmed the fundamental physical concepts and theoretical results, and have shown the promise of semiconductor structures with negative differential resistivity in uhf microelectronics.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 28–41, August, 1981.     

Vortices in an anisotropic plasma

Localized electrostatic nonlinear drift wave structures in a plasma with hot electrons and anisotropic ions are considered. The anisotropic energy distribution leads to a new nonlinearity in the evolution equation of finite amplitude drift waves. One- and two-dimensional solutions of physical interest are presented.     

Influence of an Octupole Arrangement of Electrodes on Drift Waves

In order to influence drift waves an octupole arrangement of electrodes is placed in direct vicinity of the plasma. By applying sinusoidal signals with proper phase shift to th electrodes synchronisation of drift waves is observed. The width of the synchronisation area is taken to quantify the interaction of the electrodes with the plasma. It turns out that the synchroniseability strongly depends on the frequency, amplitude and phase shift and has to be interpreted as spatiotemporal effect.     

A class of exact solutions of the Hasegawa-Mima equation

The existence of a new class of drift vortices in a cylindrical plasma pinch is demonstrated starting from an exact solution of the Hasegawa-Mima equation with an inhomogeneous drift velocity. The waves are moving in a circle in the azimuthal direction and represent either a single cyclonic motion or a pair of cyclonic-anticyclonic motions of unequal intensity.     

Rekombinationswahrscheinlichkeit und Driftgeschwindigkeit bei Zinksulfid

From a discussion of electroluminescence brightness waves of ZnS crystals of low electron concentration, it is inferred that the drift velocity of the electrons diminishes the recombination probability of electrons with holes if the drift is of the order of the Brownian particle shift corresponding to the mutual electron distance.     

Relativistic study of electromagnetic electron cyclotron instability based on trapped electrons in kappa-Maxwellian auroral plasmas

The presence of relativistic electrons in the Earth's magnetosphere may excite EMEC waves via resonant interaction. The understanding of EMEC waves induced by such electrons requires relativistic treatment. Therefore, we present here the investigation of EMEC waves based on relativistic trapped electrons represented by kappa-Maxwellian distribution in auroral plasmas. The analytical expressions of real frequency and relativistic growth rate are derived. Our numerical outcomes report that relativistic approximation increases the wave growth and causes reduction in the threshold value of drift velocity of trapped electrons for instability. The wave frequency that corresponds to the maximum growth decreases as we go from nonrelativistic limit to relativistic. The maximum growth increases with the increment in plasma frequency, perpendicular thermal velocity, drift velocity of trapped electrons, and Lorentz factor γ. Moreover, the relativistic effects on maximum growth are more pronounced for smaller values of drift velocity and perpendicular thermal velocity.     

Self-phasing of drift waves

It is shown that self-phasing can be used to generate and control large-amplitude drift waves in a magneto-plasma.     

Dust Sheared Flow Driven Instability of Dust Drift Waves in a Nonuniform Magnetoplasma

We investigate instability of dust drift waves in a nonuniform dusty magnetoplasma containing transverse sheared plasma flow that is produced by a nonuniform electric field. By using Boltzmann distributed electrons and ions, Poisson’s equation, as well as the dust continuity equation with perpendicular guiding center dust drift speed, we derive an eigenvalue equation, which strongly depends on the profiles of dust sheared flow and dust density gradient. The eigenvalue equation is analytically solved to obtain expressions for the growth rate and threshold of a convective instability arising from resonant interactions between the dust drift waves and sheared flows. The result may be relevant to the understanding of short wavelength (in comparison with the ion gyroradius) electrostatic fluctuations in magnetized plasmas of Saturn rings and in cometary tails. PACS numbers: 52.27.Lw; 52.35.Fp