Effect of Electron and/or Ion Nonthermality on Dust Acoustic Wave Propagation in a Complex Plasma in Presence of Positively Charged Dust Grains Generated by Secondary Electron Emission Process

Abstract

In this paper we have developed a model to study the role of both electron and ion nonthermalities on dust acoustic wave propagation in a complex plasma in presence of positively charged dust grains. Secondary electron emission from dust grains has been considered as the source of positive dust charging. As secondary emission current depends on the flux of primary electrons, nonthermality of primary electrons changes the expression of secondary emission current from that of earlier work where primary electrons were thermal. Expression of nonthermal electron current flowing to the positively charged dust grains and consequently the expression of secondary electron current flowing out of the dust grains have been first time calculated in this paper, whereas the expression for nonthermal ion current flowing to the positively charged dust grains is present in existing literature. Dispersion relation of dust acoustic wave has been derived. From this dispersion relation real frequency and growth rate of the wave have been calculated. Results have been plotted for different strength of nonthermalities of electrons and ions.

Experimental study of charging of dust grains in the presence of energetic electrons

“…This is reflected in the EEDFs curves as shown in figure 10. Therefore, in the present scenario, the deviation from the familiar theoretical result for the observed dust current with the increasing electron temperature might be credited to secondary electrons emitted from the dust surface [24]. Cesium coated W dust grains also show similar SEE behavior as seen in figure 10.…”

“…This indicates that the negative charge accumulated on the dust surface decreases with the increase in the discharge current. Many theoretical findings [24][25][26][27] suggest that positively charged dust is a stable state that arises due to the emission of electrons from the dust surface. D'Angelo [28] measured positively charged dust in the presence of negative ions experimentally.…”

Experimental study of charging of dust grains in presence of energetic electrons

“…This is reflected in the EEDFs curves as shown in figure 9. Therefore, in the present scenario, the deviation from the familiar theoretical result for the observed dust current with the increasing electron temperature might be credited to secondary electrons emitted from the dust surface [22]. Cesium coated W dust grains also show similar SEE behavior as seen in figure9.…”

“…This indicates that the negative charge accumulated on the dust surface decreases with the increase in the discharge current. Many theoretical findings [22,23,24,25] suggest that positively charged dust is a stable state that arises due to the emission of electrons from the dust surface. D'Angelo [26] measured positively charged dust in presence of negative ions experimentally.…”

Ion Nonthermality Induced Nonlinear Dust Acoustic Wave Propagation in a Complex Plasma in Presence of Weak Secondary Electron Emission from Dust Grains

“…Such space and astrophysical plasmas also contain huge dust grains which are charged by secondary electron emission mechanism where energetic electrons are present. Low frequency dust acoustic waves propagating in such plasmas are influenced by the nonthermality of background charge particles whose linear theory has already been studied [8] [9] [10]. Nonlinear theory considering positive equilibrium dust charge generated by secondary electron process has been recently reported [11].…”