Onset of turbulence induced by electron nonthermality in a complex plasma in presence of positively charged dust grains

Susmita Sarkar,Subrata Bhakta

doi:10.1063/1.5006155

Abstract

In this paper onset of turbulence has been detected from the study of non linear dust acoustic wave propagation in a complex plasma considering electrons nonthermal and equilibrium dust charge positive. Dust grains are charged by secondary electron emission process. Our analysis shows that increase in electron nonthermality makes the grain charging process faster by reducing the magnitude of the nonadiabaticity induced pseudo viscosity. Consequently nature of dust charge variation changes from nonadiabatic to adiabatic one. For further increase of electron nonthermality, this pseudo viscosity becomes negative and hence generates a turbulent grain charging behaviour. This turbulent grain charging phenomenon is exclusively the outcome of this nonlinear study which was not found in linear analysis.

Highlights

Dusty plasma has become an emerging field of plasma research since last three decades
On the other hand negative equilibrium dust charge state exists at low temperature when secondary electron emission from dust surface is rare and the process of collection of electrons and ions by the dust grains dominates over the secondary electron emission from the dust surface and value of the secondary electron yield is low.[3]
Inclusion of electron nonthermality is important in the study of nonlinear dust acoustic wave propagation when dust grains are charged by secondary electron emission mechanism. We have considered this effect in our present investigation for nonadiabatic dust charge variation assuming the presence of inertia less nonthermal primary and secondary electrons, thermal ions and positive equilibrium dust charge generated by frequent secondary electron emission from dust grains

Summary

INTRODUCTION

Dusty plasma has become an emerging field of plasma research since last three decades. Study of the effects of adiabatic and nonadiabatic grain charging behaviour on nonlinear wave propagation in dusty plasma is important as they give rise distinct physical situation It was studied by several authors assuming the dust charging by plasma current and equilibrium dust charge negative.[4,5,6,7,8,9,10] Charging of dust grains by secondary electron emission process in this study was first reported by us considering negative[12] as well as positive[13] equilibrium dust charges and both electrons and ions thermal. For further increase in electron nonthermality, this pseudo viscosity becomes negative at both weak and strong nonadiabaticity This negative pseudo viscosity implies that the system has become turbulent.[11] This interesting result is the outcome of the nonlinear theory of dust acoustic wave propagation obtained by considering electron nonthermality in presence of positive equilibrium dust charge generated by secondary electron emission process.

FORMULATION OF THE PROBLEM

REDUCTIVE PERTURBATION ANALYSIS

NUMERICAL ESTIMATION

CONCLUSION