Chemical model for positively charged dust particles

Abstract

A chemical model of electron-dust plasmas consisting of electrons and dust particles is systematically developed. An insight is exploited that a single dust particle forms a potential well for electrons, whose depth is determined by the work function of the dust material. The whole electron fluid, initially concentrated inside the dust particles, is somehow reallocated between the bulk of the dust matter and the ambient space available, which is then interpreted as thermionic emission. An expression is employed for the Helmholtz free energy of the system, which includes the ideal and excess parts to thoroughly deal with interactions between the dusty plasma constituents. Numerical calculations of dust particle charge are performed in quite a broad domain of plasma parameters, and a straightforward comparison is made with the orbital motion limited (OML) approximation to demonstrate that the proposed calculation scheme predicts higher positive charge values of dust grains. It is also proved that the OML approximation exactly corresponds to the ideal-gas model when interactions between plasma particles are entirely neglected.

Roles of positively charged dust, ion fluid temperature, and nonthermal electrons in the formation of modified-ion-acoustic solitary and shock waves

“…Earth's mesosphere [1][2][3], upper part of ionosphere [4,5], cometary tails [6,7], Jupiter's surroundings [8], Jupiter's magnetosphere [9], noctilucent clouds [10], etc.) and laboratory [11][12][13] dusty plasma systems, where the PCD species coexists with the electron-ion plasmas.…”

“…where ω (k) is the MIA wave angular frequency (propagation constant); C i = (z i k B T e /m i ) 1/2 is the MIA speed in which k B is the Boltzmann constant, T e is the electron temperature, and m i is the ion mass; λ D = (k B T e /4πz i n i0 e 2 ) 1/2 is the MIA wave-length scale in which n i0 (z i ) is the number density (charge state) of the ion species at equilibrium, and e is the magnitude of * Corresponding author: shikha152phy@gmail.com an electronic charge; µ = z d n d0 /z i n i0 with n d0 (z d ) being the number density (charge state) of the PCD species at equilibrium for which n e0 = z d n d0 + z i n i0 . This means that µ = 0 corresponds to the electron-ion plasma, and µ → ∞ corresponds to electron-dust plasma [7,[11][12][13]. Thus, 0 < µ < ∞ is valid for the electron-ion-PCD plasmas.…”

“…There has been a great deal of renewed interest in understanding the role of positively charged dust (PCD) species in modifying the existing features as well as in introducing new features of linear and nonlinear propagation of the modified-ion-acoustic (MIA) waves propagating in space [1][2][3][4][5][6][7][8][9][10] and laboratory [11][12][13] dusty plasma systems, where the PCD species coexists with the electron-ion plasmas. The dust species in such systems are positively charged [14] due to (i) secondary emission of electrons from the dust grain surface by the impact of high energetic plasma particles like electrons or ions [15], (ii) thermionic emission of electrons from the dust grain surface by the intense radiative or thermal heating [16], (ii) photo-emission of electrons from the dust grain surface by the interaction of high energy photons with the dust grain surface [17], etc.…”

Roles of positively charged dust in the formation of ion‐acoustic subsonic solitary waves in electron‐ion‐positively charged dust plasmas

“…We note that = 0 corresponds to the electron-ion plasma, [1,2] and → ∞ corresponds to electron-dust plasma. [28][29][30][31] The electron-dust are observed in space and laboratory experiments. [29][30][31] Thus, 0 < < ∞ is valid for the electron-ion-pcd plasmas.…”

“…[28][29][30][31] The electron-dust are observed in space and laboratory experiments. [29][30][31] Thus, 0 < < ∞ is valid for the electron-ion-pcd plasmas.…”