R. T. Faria

Linear and nonlinear dispersive Alfvén waves in two-ion plasmas

A set of coupled nonlinear equations for dispersive Alfven waves (DAWs) in nonuniform magnetoplasmas with two-ion species is derived by employing a multifluid model. The DAW frequency is assumed to lie between the gyrofrequencies of the light and heavy ion impurities. In the linear limit, a local dispersion relation (LDR) is derived and analyzed. The LDR admits a new type of DAW in two-ion plasmas. Furthermore, it is found that stationary solutions of the nonlinear mode coupling equations in two-ion plasmas can be represented in the form of different types of coherent vortex structures. The relevance of our investigation to space and laboratory plasmas is pointed out.

Parallel ion velocity shear driven electromagnetic fluctuations and associated particle transport in partially ionized plasmas

A nonuniform partially ionized magnetized plasma is shown to be unstable against electromagnetic perturbations. The source of free energy for the instability is sheared magnetic-field-aligned ion flow, which is coupled to the electromagnetic waves via charged particle-neutral collisions. Analytical expressions for the growth rate and threshold are obtained. Numerical studies for the ionospheric parameters suggest that electromagnetic waves grow faster than their electrostatic counterparts. Furthermore, linearly excited electromagnetic waves in partially ionized collisional plasmas are shown to cause nonthermal cross-field transport of plasma particles. The results can have relevance to the current filament at ion and the plasma diffusion in the ionosphere of the Earth, as well as in low-temperature laboratory plasmas.

A class of stationary nonlinear dusty plasma equilibria

It is shown that nonparallel density and temperature gradients can produce magnetic fields in dusty plasmas. Spontaneously created magnetic fields can be maintained if there exists plasma vorticity. In order to understand this phenomena, a self-consistent dusty plasma equilibrium model is constructed by employing a kinetic description and invoking the Hamiltonian approach. Stationary nonlinear dusty plasma equilibria contain specific profiles for the plasma number density, the plasma current, and the magnetic field. The relevance of this investigation to low-temperature laboratory dusty and space plasmas is discussed.

Modulational instability of random phase plasmons in collisional plasmas

The modulational instability of random phase Langmuir waves in an unmagnetized collisional plasma is investigated. The growth rate of the instability is presented in several interesting limiting cases. The relevance of this investigation to space and laboratory plasmas is pointed out.

Nonlinear dynamics of electromagnetic turbulence in a nonuniform magnetized plasma

By using the hydrodynamic electron response with fixed (kinetic) ions along with Poisson’s equation as well as Ampere’s law, a system of nonlinear equations for low-frequency (in comparison with the electron gyrofrequency) long-(short-) wavelength electromagnetic waves in a nonuniform resistive magnetoplasma has been derived. The plasma contains equilibrium density gradient and sheared equilibrium plasma flows. In the linear limit, local dispersion relations are obtained and analyzed. It is found that sheared equilibrium flows can cause instability of Alfven-like electromagnetic waves even in the absence of a density gradient. Furthermore, it is shown that possible stationary solutions of the nonlinear equations without dissipation can be represented in the form of various types of vortices. On the other hand, the temporal behavior of our nonlinear dissipative systems without the equilibrium density inhomogeneity can be described by the generalized Lorenz equations which admit chaotic trajectories. The de...

Chaos in the parallel sheared plasma flow driven electromagnetic turbulence in nonuniform magnetoplasmas

By employing the two-fluid model, a system of nonlinear equations for low-frequency electromagnetic waves in nonuniform collisional magnetoplasmas has been derived. The plasma contains both the equilibrium density gradient and sheared flows. In the linear limit, a local dispersion relation has been obtained and analyzed in several interesting limiting cases. It is found that equilibrium sheared plasma flows cause instabilities of Alfven-type waves even in the absence of the density gradient. The numerical results also show a large growth rate of electromagnetic parallel velocity shear (PVS) mode compared to the electrostatic mode for some ionospheric parameters. For this case, the temporal nonlinear behavior of the relevant governing mode coupling equations is governed by six coupled equations, which are a generalization of the Lorenz–Stenflo equations and which admit chaotic trajectories. The results of this investigation should be useful for understanding the linear and nonlinear properties of electroma...

Evolution of Electron‐Acoustic Wave in Auroral Region

Broadband noise in auroral region is related to an interesting coupled mode, namely, electron‐acoustic and kinetic Alfven coupled mode, which are derived from a set of nonlinear equations for low‐frequency short wavelength electromagnetic waves in a nonuniform magnetized plasma with sheared plasma flows. In the linear limit it is found that sheared equilibrium flows can be the cause of instability of Alfven‐like electromagnetic waves and electron‐acoustic waves in magnetospheric measurements. It is also shown that possible stationary solutions of the nonlinear equations without dissipation can be represented in the form of novel electron‐acoustic street vortices.

Order and chaos in ETG-driven drift–dissipative waves with sheared flows

We derive a system of nonlinear equations that govern the dynamics of low-frequency short-wavelength electromagnetic waves in the presence of equilibrium density, temperature, magnetic field and velocity gradients. In the linear limit, a local dispersion relation is obtained and analyzed. New η e -driven electromagnetic drift modes and instabilities are shown to exist. In the nonlinear case, the temporal behaviour of a nonlinear dissipative system can be written in the form of Lorenz- and Stenflo-type equations that admit chaotic trajectories. On the other hand, the stationary solutions of the nonlinear system can be represented in the form of dipolar and vortex-chain solutions.

Drift-ballooning modes in the presence of charged dust impurities in a nonuniform rotating magnetoplasma

The linear and nonlinear properties of drift-ballooning modes in the presence of an equilibrium electric field and stationary charged dust grains are examined. It is found that the presence of these two contribute to the stability of the ballooning mode. Furthermore, the nonlinear coupling between finite amplitude drift-ballooning modes gives rise to different types of coherent vortex structures, which can affect the transport properties of an inhomogeneous magnetized plasma. The relevance of the investigation to laboratory and astrophysical plasmas is discussed.

Self-organized and chaotic states in nonuniform dusty magnetoplasmas with sheared flows

It is well known that sheared plasma flows can be built up both in astrophysical environments as well as in laboratory dusty plasmas. Our objective here is to understand the coupling of velocity gradient energy to electrostatic and electromagnetic waves in nonuniform dusty magnetoplasma. For this purpose, we employ the multi-fluid dusty plasma model and derive the relevant nonlinear equations for low-frequency (in comparison with the ion gyrofrequency) waves in the presence of sheared plasma flows. Linear dispersion relations are derived and analyzed. It is found that both the electrostatic and electromagnetic waves are driven by sheared plasma flows. Furthermore, the newly derived mode coupling equations provide the possibility of self-organized and chaotic states in dusty plasmas. The results of our investigation should be helpful in understanding the properties of dusty plasma microturbulence when sources and sinks are simultaneously present.