Using the reductive perturbation method, we present a theory for dust–acoustic nonlinear periodic waves, namely dust–acoustic cnoidal waves, in a plasma containing hot electrons and ions, and warm dust grains with varying charge. It is found that the frequency of the cnoidal wave is a function of its amplitude. It is also found that the dust grain charge fluctuation and other plasma parameters modify the properties of the dust–acoustic cnoidal waves. In the limiting case, these dust–acoustic cnoidal waves reduce to the well-known dust–acoustic solitons.

A dusty plasma consisting of negatively charged cold dust, adiabatic hot ions, and inertia-less adiabatic hot electrons has been considered. The adiabatic effects of electrons and ions on the basic properties of electro-acoustic solitary waves associated with different types of electro-acoustic (viz. ion-acoustic (IA), dust ion-acoustic (DIA), and dust acoustic (DA)) waves are thoroughly investigated by the reductive perturbation method. It is found that the basic properties of the IA, DIA, and DA waves are significantly modified by the adiabatic effects of ions and inertia-less electrons. The implications of our results in space and laboratory dusty plasmas are briefly discussed.

The usual theory of plasma relaxation, based on the selective decay of magnetic energy over the (global) magnetic helicity, predicts a force-free state for a plasma. Such a force-free state is inadequate to describe most realistic plasma systems occurring in laboratory and space plasmas as it produces a zero pressure gradient and cannot couple magnetic fields with flow. A different theory of relaxation has been proposed by many authors, based on a well-known principle of irreversible thermodynamics, the principle of minimum entropy production rate which is equivalent to the minimum dissipation rate of energy. We demonstrate the applicability of minimum dissipative relaxed states to various self-organized systems of magnetically confined plasma in the laboratory and in the astrophysical context. Such relaxed states are shown to produce a number of basic characteristics of laboratory plasma confinement systems and solar arcade structure.

We consider an adiabatic dusty plasma containing adiabatic inertialess electrons, adiabatic ions, and adiabatic negatively charged dust. The basic features of the dust–ion-acoustic (DIA) as well as the dust-acoustic (DA) solitary waves (SWs) in such an adiabatic dusty plasma are investigated using the reductive perturbation method, which is valid for small amplitude SWs, and by the pseudo-potential approach which is valid for arbitrary amplitude SWs. The combined effects of the adiabaticity of electrons/ions and negatively charged static/mobile dust on the basic features (polarity, speed, amplitude and width) of small as well as arbitrary amplitude DIA and DA SWs are examined explicitly. It is found that the combined effects of the adiabaticity of electrons/ions and negatively charged static/mobile dust significantly modify the basic features (polarity, speed, amplitude and width) of the DIA and DA SWs. The implications of our results in space and laboratory dusty plasmas are discussed briefly.

The reflection of an obliquely incident electromagnetic pulse from a moving plasma half-space is studied. Using the Lorentz transformations, covariance of Maxwell's equations and the principle of phase invariance to transform between the rest frame and the moving frame, calculations can be conveniently performed in the moving frame. An analytical formula for the linear reflected waveform as a function of the incident angle shows temporal compression and pulse amplification at relativistic velocities of relevance for the generation of ultra-short laser optical pulses.

A linear theory of whistler waves is developed within the paradigm of a two-dimensional incompressible electron magnetohydrodynamics model. Exact analytic wave solutions are obtained for small-amplitude whistler waves that exhibit magnetic field topological structures consistent with the observations and our simulations in a linear regime. In agreement with experiment, we find that the parallel group velocity of the wave is large compared to its perpendicular counterpart. Numerical simulations of collisional interactions demonstrate that the wave magnetic field either coalesces or repels depending upon the polarity of the associated current. In the nonlinear regime, our simulations demonstrate that the evolution of the wave magnetic field is governed essentially by the nonlinear Hall force.

Simulations are performed to investigate the turbulent properties of nonlinearly interacting two-dimensional magnetic electron drift vortex (MEDV) modes in a non-uniform unmagnetized plasma. The relevant nonlinear equations governing the dynamics of the MEDV modes are the wave magnetic field and electron temperature perturbations in the presence of the equilibrium density and temperature gradients. The important nonlinearities come from the advection of the electron fluid velocity perturbation and the electron temperature, as well as from the nonlinear electron Lorentz force. Computer simulations of the governing equations for the nonlinear MEDV modes reveal the generation of streamer-like electron flows, such that the corresponding gradients in the direction of the inhomogeneities tend to flatten out. In contrast, the gradients in an orthogonal direction vary rapidly. Consequently, the inertial range energy spectrum in decaying MEDV mode turbulence exhibits a much steeper anisotropic spectral index. The magnetic structures in the MEDV mode turbulence produce non-thermal electron transport in our non-uniform plasma.