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

Sharmin Jahan,Abdul Mannan,Rubaiya Khondoker Shikha,A A Mamun

doi:10.3390/plasma5010001

Sharmin Jahan, Abdul Mannan + Show 2 more

Open Access

https://doi.org/10.3390/plasma5010001

Copy DOI

Journal: Plasma	Publication Date: Dec 29, 2021
Citations: 2	License type: CC BY 4.0

Affiliation: Jahangirnagar University

Abstract

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.

Highlights

The physics of pair-ion (PI) plasmas, which have unusual thermodynamic features due to the presence of solely positively and negatively charged species of equal mass [1], has received tremendous attention in recent years as their applications have progressed from the astronomical realm to the terrestrial laboratory
Work by examining the conditions for the modulational instability (MI) in a four-component plasma system, using the reductive perturbation method (RPM) of the ion-acoustic solitary (IAS) waves
We have considered an unmagnetized, fully ionized, and four-component PI plasma model consisting of inertial positive ions, following the fluid–momentum equations, inertial negative ions, explained by the fluid–dynamic equations, inertialess electrons, assumed to obey a non-thermal, non-extensive distribution, and an inertialess positron, denoted by n p, that follows an iso-thermal distribution

Summary

Introduction

The physics of pair-ion (PI) plasmas, which have unusual thermodynamic features due to the presence of solely positively and negatively charged species of equal mass [1], has received tremendous attention in recent years as their applications have progressed from the astronomical realm to the terrestrial laboratory. Employed a q-non-extensive, non-thermal electron velocity distribution to explore the MI of IAWs, and discovered that plasma supports both the bright and dark envelope solitons. They discovered that the valid domain for the wave number k, at which instabilities occur, differs depending on both the entropic index q and the non-thermal parameter α. Work by examining the conditions for the MI in a four-component plasma system, using the RPM of the IAS waves (in which inertia is provided by the ion masses and restoring force is regulated by the thermal pressure of non-thermal, non-extensive q-distributed electrons and iso-thermal positrons).

Model Equations

Stability of IAWs

Envelope Solitons

Conclusions