Drift-dissipative Instability Research Articles

Local analysis of electrostatic modes in a two-fluid E×B plasma

A local study of linear electrostatic modes, applicable to the dynamics perpendicular to the magnetic field in a plasma with crossed electric and magnetic fields, is presented. The analysis is based on a two-fluid model that takes into account the finite-electron-gyroradius effects through a rigorous gyroviscosity tensor and includes a dissipative friction force in the electron momentum equation. A comprehensive dispersion relation, valid for arbitrary electron temperature, is derived, which describes properly all the relevant waves for wavelengths longer than the electron Larmor radius. For a homogeneous and dissipationless plasma, such a fluid dispersion relation agrees with the long-wavelength limit of the kinetic electron–cyclotron-drift instability dispersion relation that extends the results to arbitrary short wavelengths. The general fluid dispersion relation covers different parametric regimes that depend on the relative ion-to-electron drift velocity and on the presence of equilibrium inhomogeneities and/or dissipation. Depending on such conditions, its roots yield as follows: two-stream instabilities, driven solely by the relative drift between species; drift-gradient instabilities, driven by the combination of the relative drift and equilibrium gradients; and drift-dissipative instabilities, driven by the combination of the relative drift and friction. Instability thresholds are determined and some distinctive unstable modes are described analytically.

To the question about mechanisms for the formation of dust fractal structures from an arc plasma

The paper presents the results obtained in the study of dusty particles of an arc discharge plasma (fractal aggregates). One of the possible reasons for the formation of fractal structures is the current layers. These are ion flows between adjacent cathode spots of an arc discharge. The magnetic field of the current sheet is an energy source, the dissipation of which leads to the creation of instability of the growth front. In this area, the formation of fractal-like aggregates (drift-dissipative instability) can occur.

Characteristics of the Growth Increment of Drift-Dissipative Instability at the Fronts of Equatorial Plasma Bubbles

Data from ground-based and satellite measurements, as well as the results of numerical modeling of the spatial structure of equatorial ionospheric bubbles, show that the longitude gradients of the logarithm of the electron concentration at the vertical boundaries of the bubbles can reach 10–3 m–1. At such electron concentration gradients, the development of drift-dissipative instability is possible. This can generate ionospheric plasma inhomogeneities with spatiotemporal scales characteristic of the equatorial F scatter. This article presents the results of calculations of the increment of the increase in gradient-drift instability on the side walls of ionospheric bubbles obtained on the basis of numerical modeling of the structure of equatorial plasma bubbles and the dispersion equation of drift-dissipative instability. The equatorial plasma bubbles were simulated on the basis of a two-dimensional numerical model of the Rayleigh-Taylor instability in the Earth’s equatorial ionosphere, which is suitable for modeling Rayleigh-Taylor and gradient type inhomogeneities that are strongly elongated along the magnetic field lines. The results of numerical experiments confirm that significant longitudinal plasma gradients at the fronts of the developed equatorial plasma bubble can generate drift-dissipative instability of the ionospheric plasma.

Physical Effects of the Lipetsk Meteoroid: 3

Comprehensive modeling studies of the processes induced in all geospheres by the passage and explosion of the meteoroid near the city of Lipetsk (Russia) on June 21, 2018, have been conducted. Magnetic, electric, electromagnetic, ionospheric, and seismic effects, as well as the effects of acoustic-gravity waves have been estimated. The magnetic effect of turbulence has been shown to be insignificant. The magnetic effect of the ionospheric currents and the current in the wake of the meteoroid could be substantial (~1 nT). Under the action of an external electric field, a transient current pulse with the strength of current up to 104 A could occur. The electrostatic effect could be accompanied by the accumulation of an electric charge of 1 mC producing the electric field intensity of 0.01–1 MV/m. The flow of the electric current in the wake of the meteoroid could result in the generation of an electromagnetic pulse in the 40–80 kHz band with the electric field intensity of 1–10 V/m. The electromagnetic effect of infrasound has been determined to be significant (1–10 V/m and 1–10 nT). The absorption of the shock wave at ionospheric dynamo region altitudes (100–150 km) could generate secondary atmospheric gravity waves with the 0.1–1 relative amplitude. The passage of the meteoroid acted to produce a plasma wake and noticeable disturbance not only in the lower but also in the upper atmosphere in the range of no less than 1000 km. The possibility of occurrence of the electrophonic effect, the generation of the ion and magnetic sound by infrasound, and the generation of gradient-drift and drift-dissipative instabilities are discussed. A conclusion is drawn that magnetic, electric, and electromagnetic effects dealt with in this paper significantly fill in the gaps in the theory of physical effects produced by meteoroids in the Earth–atmosphere–ionosphere–magnetosphere system. The magnitudes of magnetic, electric, electromagnetic, ionospheric, and acoustic effects were significant. The magnitude of the earthquake caused by the meteoroid explosion did not exceeded 1.7. The mean rate of the fall of celestial bodies similar to the Lipetsk meteoroid is equal to 0.68 yr–1.

Drift dissipative instability in a dusty plasma: Do dust particles reduce intensity of density irregularities in the lower ionosphere?

We re-analyzed the effect of loss of electrons and hence the reduction in electron density on drift dissipative instability. We find that the growth rates of the drift waves decrease. The analysis suggests that the presence of dust particle, if they are responsible for the loss of background electrons, will reduce the intensity of density irregularities in the E region of the ionosphere.

A note on the drift waves in the presence of electrons added by meteors by ablation phenomena or by thermionic emissions

The role of added electrons on the drift dissipative instability in a nonuniform collisional plasma is analysed. We observe the presence of a drift wave that depends entirely on the added electrons through the collision frequency coupling and there is an additional damping. The present study is applied to the density irregularities caused by meteor ionization in the ionosphere.

Drift wave excitation in a collisional dusty magnetoplasma with multi-ion species

AbstractWe investigate the drift dissipative instability in a non-uniform magnetized plasma composed of electrons, positive ions, negative ions and negatively charged dust particles. We use a multi-fluid plasma model and derive a dispersion relation for the electrostatic drift waves with frequencies much smaller than the ion gyrofrequencies and wavelengths longer than the ion gyroradii. The presence of the negatively charged, massive dust grains affects the drift wave frequency and the growth rate of the drift dissipative instability. The present results may be relevant to space and laboratory magnetoplasmas containing negative ions and charged dust grains.

Linear and nonlinear drift waves in collisionless and collisional electron-positron-ion plasmas

The linear and nonlinear drift waves in collisional and collisionless electron-positron-ion plasmas are studied in the classical limit. The possibilities of formation of solitons and shocks under different conditions are discussed. To estimate the growth rate of the linear drift dissipative instability in this case is not straightforward. However, in a limiting case it can be calculated exactly. Comparison of the results with the usual electron-ion plasmas is presented and the behavior of linear and nonlinear dynamics is pointed out for applications to laboratory and astrophysical situations.

Electrostatic instabilities and nonlinear structures of low-frequency waves in nonuniform electron–positron–ion plasmas with shear flow

It is found that the low-frequency ion acoustic and electrostatic drift waves can become unstable in uniform electron–ion and electron–positron–ion plasmas due to the ion shear flow. In a collisional plasma a drift-dissipative instability can also take place. In the presence of collisions the temporal behavior of nonlinear drift-dissipative mode can be represented in the form of well-known Lorenz and Stenflo type equations that admit chaotic trajectories. On the other hand, a quasi-stationary solution of the mode coupling equations can be represented in the form of monopolar vortex. The results of the present investigation can be helpful in understanding electrostatic turbulence and wave phenomena in laboratory and astrophysical plasmas.

Studies of fluctuations in the high-temperature plasma of modern stellarators by the microwave scattering technique

Microwave scattering diagnostics are described that allow direct measurements of the turbulent processes in the high-temperature plasma of magnetic confinement systems. The first physical results are presented from fluctuation measurements carried out in 2000–2001 in three stellarators: L-2M (Institute of General Physics, Moscow), LHD (National Institute of Fusion Science, Toki), and TJ-II (CIEMAT, Madrid). Plasma density fluctuations in the axial (heating) regions of the L-2M and LHD stellarators were measured from microwave scattering at the fundamental harmonic of the heating gyrotron radiation. In the TJ-II stellarator, a separate 2-mm microwave source was used to produce a probing beam; the measurements were performed at the middle of the plasma radius. Characteristic features of fluctuations, common for all three devices, are revealed by the methods of statistical and spectral analysis. These features are the wide frequency Fourier and wavelet spectra, autocorrelation functions with slowly decreasing tails, and non-Gaussian probability distributions of the magnitudes and the increments in the magnitude of fluctuations. Observations showed the high level of coherence between turbulent fluctuations in the central region and at the edge of the L-2M plasma. The drift-dissipative instability and the instability driven by trapped electrons are examined as possible sources of turbulence in a high-temperature plasma.

Measurements of Electric Charge and Degree of Nonquasineutrality in Plasma Oscillations at the Instability

Experiments were carried out on determination of the electric charge and degree of nonquasineutrality in plasma oscillations. These measurements were performed in unstable plasma in the absence of temperature fluctuations when drift-dissipative instability in a magnetic field developed.

Drift dissipative instability in planetary and cometary dusty plasmas

In a magnetized inhomogeneous dusty plasma drift dissipative instability may play an important role. We have examined the dependence of frequencies and growth rates on dust parameters. The marginal instability for such a dusty plasma seems to show some interesting results. The relevance of the investigation is discussed to understand the wave phenomena in planets and cometary environments.

Drift dissipative instabilities in hybrid frequency range

The instabilities of electron convection mode in a collisional plasma including electromagnetic effects are investigated. It is found that all the three solutions of the linear-dispersion relation are unstable. It is shown that the ion temperature fluctuations can play a stabilizing role. An application to a typical low-temperature plasma is discussed.

The role of nonquasineutrality in instable plasma oscillations

Nonquasineutrality in perturbations has a destabilising influence on a plasma which is not in thermodynamic equilibrium and has a density gradient across a homogeneous axial magnetic field. This destabilising effect applies not only to short but also to long drift–dissipative instability waves. If long drift waves are excited, nonquasineutrality can also destabilise a plasma simultaneously with ion inertia. In strong magnetic fields the absence of quasineutrality of perturbations is important even when the density of charged particles is high.

Drift-dissipative instability of the electromagnetic convection mode in a low-temperature plasma

The convection mode in a collisional plasma is investigated, with the inclusion of electromagnetic effects. It is shown that a dissipative instability can occur. The relationship to several well-known modes as well as applications to typical low-temperature plasmas are discussed.

Phenomenological description of nonlinear waves produced by the drift-dissipative instability of a magnetized inhomogeneous plasma

A one-dimensional phenomological equation to describe nonlinear evolution of drift waves generated by dissipative instability of a magnetized plasma with density inhomogeneous across the magnetic field is proposed. A set of solutions describing monochromatic traveling waves is obtained together with conditions providing their full stability against small perturbations. Some approximate results concerning the stability against finite perturbations are also obtained. Then a collision between two asymptotically (at x → ± ∞) monochromatic waves is considered. It is demonstrated that the collision always results in suppressing a wave with a smaller wavenumber and a larger amplitude by a wave with a larger wavenumber and a smaller amplitude, what suggests a way to reduce the instability-induced transfer of heat and particles in fusion plasmas.

Electron Acoustic and Lower Hybrid Drift Dissipative Instabilities in a Multi-Ion Species Plasma

Drift dissipative instabilities of electron-acoustic and lower-hybrid wave in a multi-ion species plasma have been investigated. In contrast to the result of Mohan and Yu [15], it is found that the electron-acoustic drift dissipative instability appears at moderately high ion-viscosity. Also we have found another electron-acoustic drift dissipative mode due to second ion species which is also having a growth rate of same order.

Drift dissipative instabilities between the electron and ion cyclotron frequencies

The possible existence of drift dissipative instabilities in an inhomogeneous, collisional plasma with frequencies in the range Ωi ≪Re ω≪Ωe is investigated. It is shown that drift modes associated with lower-hybrid and electron-acoustic waves are stabilized by ion collisional damping when the electrons are cold but that unstable waves can exist when the electrons are warm.

Influence of RF on ion drift dissipative instabilities

Ion drift and ion cyclotron drift waves have been observed in the density gradient of a plasma column. Launching RF near the lower hybrid frequency into the plasma results in a suppression of the ion drift waves and a parametric amplification of the ion cyclotron drift waves. Spectral analysis of probe signals monitoring the plasma density fluctuations demonstrates the importance of three wave coupling for the saturation of the observed instabilities.

The “drift dissipative instability”: a critique

This paper is a critique of Kadomtsev's fluid dispersion equation for electrostatic drift instabilities in a plasma with weak BGK charged-neutral collisions. The numerical solution of this equation is compared with the solution of a more exact kinetic dispersion equation. At maximum growth rate, the fluid results do not correspond to the kinetic results in either the collisionless or the collision-dominated limits. Thus in the BGK model of charged-neutral collisions, the “drift dissipative instability” is not a distinct mode, but only an approximation to the universal density drift instability in a limited range of parameter space.