Waves In Pair-ion Plasma Research Articles

Modulational Instability of Ion-Acoustic Waves in Pair-Ion Plasma

The modulational instability (MI) of ion-acoustic waves (IAWs) is examined theoretically in a four-component plasma system containing inertialess electrons featuring a non-thermal, non-extensive distribution, iso-thermal positrons, and positively as well as negatively charged inertial ions. In this connection, a non-linear Schrödinger equation (NLSE), which dominates the conditions for MI associated with IAWs, is obtained by using the reductive perturbation method. The numerical analysis of the NLSE reveals that the increment in non-thermality leads to a more unstable state, whereas the enhancement in non-extensivity introduces a less unstable state. It also signifies the bright (dark) ion-acoustic (IA) envelope solitons mode in the unstable (stable) domain. The conditions for MI and its growth rate in the unstable regime of the IAWs are vigorously modified by the different plasma parameters (viz., non-thermal, non-extensive q-distributed electron, iso-thermal positron, the ion charge state, the mass of the ion and positron, non-thermal parameter α, the temperature of electron and positron, etc.). Our findings may supplement and add to prior research in non-thermal, non-extensive electrons and iso-thermal positrons that can co-exist with positive as well as negative inertial ions.

Magnetoacoustic Nonlinear Solitary and Freak Waves in Pair-Ion Plasma

Abstract An investigation of magnetoacoustic nonlinear solitary and freak waves in a magnetised collisionless pair-ion plasma using two-dimensional magnetohydrodynamic model is presented. The reductive perturbation method is used to obtain the Kadomtsev–Petviashvili (KP) equation. The solitary wave solution of KP equation is examined. Further, on modulating KP equation, the nonlinear Schrödinger equation is derived with the help of appropriate transformation. The influence of various plasma parameters such as magnetic field strength, number density of ions, and temperature ratio of negative to positive ions, etc. on the propagation characteristics of solitary waves and first- as well as second-order magnetoacoustic freak waves in pair-ion plasma is examined.

Time-fractional Schamel–KdV equation for dust-ion-acoustic waves in pair-ion plasma with trapped electrons and opposite polarity dust grains

Nonlinear propagation of dust-ion-acoustic (DIA) waves is investigated in a one-dimensional, unmagnetized plasma containing positive ions, negative ions, trapped electrons featuring vortex-like distribution, and immobile dust grains having both positive and negative charges. Via reductive perturbation method, Agrawal's method, and Euler–Lagrange equation, the time-fractional Schamel–KdV equation under the sense of Riesz fractional derivative is derived to describe nonlinear behavior of DIA waves. The approximate solution of the time-fractional Schamel–KdV equation is constructed in terms of Jacobi elliptic functions by variational iteration method. The effect of the plasma parameters on the DIA solitary waves is also discussed in detail.

Electrostatic Solitary Waves in Pair-ion Plasmas with Trapped Electrons

Electrostatic solitons in an unmagnetized pair-ion plasma comprising adiabatic fluid positive and negative ions and non-isothermal electrons are investigated using both arbitrary and small amplitude techniques. An energy integral equation involving the Sagdeev potential is derived, and the basic properties of large amplitude solitary structures are investigated. Various features of solitons differ in different existence domains. The effects of ion adiabaticity, particle concentration, and resonant electrons on the profiles of Sagdeev potential and corresponding solitary waves are investigated. The generalized Korteweg-de Vries equation with mixed-nonlinearity is derived by expanding the Sagdeev potential. Asymptotic solutions for different orders of nonlinearity are discussed for solitary waves. The present work is applicable to understanding the wave phenomena and associated nonlinear electrostatic perturbations in pair/bi-ion plasmas which may occur in space and laboratory plasmas.

Properties of linear and nonlinear ion thermal waves in a pair ion plasma containing charged dust impurities

Properties of linear and nonlinear ion thermal waves (ITWs) in pair ion plasmas containing a fraction of stationary charged (positive or negative) dust grains are investigated. For this purpose, a linear dispersion relation, a Korteweg-de Vries equation and (an energy integral of a classical potential) for linear (nonlinear) ITWs are derived from the ion continuity and momentum equations together with the Poisson equation. It is found that both the ITW frequency and the profile of the ion thermal solitary waves are significantly affected by the presence of positively/negatively charged dust grains. The present results should be useful in understanding the salient features of finite amplitude localized ion thermal solitary pulses in a pair ion plasma containing charged dust impurities.

On some properties of linear and nonlinear waves in pair-ion plasmas

It is pointed out that the observation of the electrostatic ion acoustic wave frequency can be a suitable check to determine whether the produced plasma is a pure pair-ion plasma or whether it comprises some concentration of electrons. A theoretical model for the pair-ion plasma dynamics is presented along with a new electrostatic mode which can exist only in such systems. It can become unstable in the presence of shear flow and it can give rise to vortex structures in the nonlinear regime. The possibility of shocks and solitons, due to nonlinear drift waves in a pair-ion plasma comprising electrons, is also discussed. The relevance of this investigation to both laboratory and astrophysical plasmas is pointed out.