We discuss the dispersive properties of low-frequency electromagnetic (EM) perturbations in the magnetized core of self-gravitating white dwarf stars with ultra-relativistic degenerate electrons. For our purposes, we derive a dispersion relation by using the hydrodynamic equations for the ions under the action of EM and self-gravitating forces, and the inertialess electrons under the action of EM forces and the gradient of the ultra-relativistic pressure. The dispersion relation admits stability of a white dwarf star against a class of EM perturbations whose wavelengths are shorter than 15000 km.

The heliosphere is predominantly a partially ionized plasma that consists of electrons, ions and significant neutral atoms. Nonlinear interactions among these species take place through direct collision or charge-exchange processes. These interactions modify linear and nonlinear properties of the plasma. In this work, we develop a one-dimensional linear theory to investigate linear instabilities in such a system. In our model, the electrons and ions are described by a single fluid compressible magnetohydrodynamic (MHD) model and are coupled self-consistently to the neutral fluid via compressible hydrodynamic equations. The coupling is mediated by the charge-exchange process. Based on our self-consistent analysis, we find that the charge-exchange coupling is more effective at larger length scales, and the Alfvén waves are not affected by the charge-exchange coupling. By contrast, the fast and slow waves are driven linearly unstable.

A new equation of motion that governs weakly nonlinear phenomena in ideal magnetohydrodynamics (MHDs) is derived as a natural extension of the well-known linearized equation of motion for the displacement field. This derivation is made possible by expanding the MHD Lagrangian explicitly up to third order with respect to the displacement of plasma, which necessitates an efficient use of the Lie series expansion. The resultant equation of motion (i.e. the Euler–Lagrange equation) includes a new quadratic force term which is responsible for various mode–mode coupling due to the MHD nonlinearity. The third-order potential energy serves to quantify the coupling coefficient among resonant three modes and its cubic symmetry proves the Manley–Rowe relations. In contrast to earlier works, the coupling coefficient is expressed only by the displacement vector field, which is already familiar in the linear MHD theory, and both the fixed and free boundary cases are treated systematically.

The basic features and multi-dimensional instability of electrostatic solitary waves propagating in an ultra-relativistic degenerate dense magnetized plasma have been investigated by the reductive perturbation method and the small-k perturbation expansion technique. The Zakharov–Kuznetsov (ZK) equation has been derived, and its numerical solutions for some special cases have been analysed to identify the basic features (viz. amplitude, width, instability, etc.) of these electrostatic solitary structures. The implications of our results in some compact astrophysical objects, particularly white dwarfs and neutron stars, have been briefly discussed.

Through particle-in-cell simulations, the evolution of the bump-on-tail instability (BoTI) is studied for plasma subject to one-dimensional mechanical compression. It is shown that the final state of BoTI differs from that described by quasilinear theory for stationary bulk plasma and can depend on the compression history. The transformation of thermal energy into wave energy increases the plasma compressibility, thereby decreasing the amount of mechanical work required to compress the plasma to a specified size. Also, the energy spectrum of the excited modes can be tailored by choosing a particular compression scenario, offering a new technique for manipulating plasmas mechanically.

The theoretical study of microwave characteristics of a thin film of hydrogen plasma in carbon nanotubes, which were grown by iron-catalyzed high-pressure carbon monoxide disproportionation, is presented. The system is assumed to be illuminated by either a transverse magnetic (TM) or a transverse electric (TE) waves at an arbitrary angle of incidence to the film. By considering the interference effects because of multiple reflections between thin plasma layer interfaces, the reflectance, transmittance, and absorptance of microwave radiation at the plasma film are deduced and their functional dependence on the continuous changing of the angle of propagation and plasma thickness with fixed parameters of the system are studied. The simulation results show that for the present system, the interference effects lead to a sinusoidal variation of the reflected intensity and can greatly reduce the amount of reflection power, but the absorption power increases. In addition, it is found that the TE and TM waves have largely indistinguishable microwave absorption and transmission spectrums.

The generalized dispersion equation for superluminal transverse oscillation in an unmagnetized, collisionless, isotropic and relativistic plasma with non-extensive q-distribution is derived. The analytical dispersion relation is obtained in an ultra-relativistic regime, which is related to q-parameter and temperature. In the limit q → 1, the result based on the relativistic Maxwellian distribution is recovered. Using the numerical method, we obtain the full dispersion curve that cannot be given by an analytic method. It is shown that the numerical solution is in good agreement with the analytical result in the long-wavelength and short-wavelength region for ultra-relativistic plasmas.

This paper focuses on the progress in understanding the shielding around a test charge in the presence of ion-acoustic waves in multispecies plasmas, whose constituents are positive ions, two negative ions, and Boltzmann distributed electrons. By solving the linearized Vlasov equation with Poisson equation, the Debye–Hückel screening potential and wakefield (oscillatory) potential distribution around a test charge particle are derived. It is analytically found that both the Debye–Hückel potential and the wakefield potential are significantly modified due to the presence of two negative ions. The present results might be helpful to understand and to form new materials from plasmas containing two negative ions such as Xe+ − F− − SF−6 and Ar+ − F− − SF−6 plasmas, as well as to tackle extension of the test charge problem in multinegative ions' coagulation/agglomeration.

The minimum breakdown requirement in magnetic field-driven sources, like inductively coupled plasmas, is examined. The minimum breakdown requirement is dominated by the ionization energy of the considered element. Therefore, a zinc plasma is relatively difficult to ignite compared to other metal plasmas.

Stabilities, instabilities and turbulences have always appeared into a cylindrical magnetized argon plasma. These phenomena are caused by linear or nonlinear dynamics and are interpreted with the linear or nonlinear theory accordingly. In this paper, an experimental study accompanied by theoretical justification and based on the wave–wave interaction has been made; an azimuthally moved driving wave is enforced in a very simple way. The turbulence stabilization, the wave coupling, the instability synchronization and other wavy interactions, which are caused by using an external spatiotemporal electric signal, are presented. The research of the wavy subjects continuing in our laboratory aspires to comprehend the plasma chaotic behavior and take a step into suppressing the unstable inclination.

In this paper, we study the weakly-compressive high-frequency plasma waves which are superposed on a large-amplitude Alfvén wave in a multi-fluid plasma consisting of protons, electrons, and alpha particles. For these waves, the plasma environment is inhomogenous due to the presence of the low-frequency Alfvén wave with a large amplitude, a situation that may apply to space plasmas such as the solar corona and solar wind. The dispersion relation of the plasma waves is determined from a linear stability analysis using a new eigenvalue method that is employed to solve the set of differential wave equations which describe the propagation of plasma waves along the direction of the constant component of the Alfvén wave magnetic field. This approach also allows one to consider weak compressive effects. In the presence of the background Alfvén wave, the dispersion branches obtained differ significantly from the situation of a uniform plasma. Due to compressibility, acoustic waves are excited and couplings between various modes occur, and even an instability of the compressive mode. In a kinetic treatment, these plasma waves would be natural candidates for Landau-resonant wave–particle interactions, and may thus via their damping lead to particle heating.

The effect of radial boundaries on the ion-dust streaming instability is investigated. Possible applications of our work to certain low-temperature dusty plasma experiments are discussed.