Ion- and electron-acoustic solitons in two-electron temperature space plasmas

Abstract

Properties of ion- and electron-acoustic solitons are investigated in an unmagnetized multi-component plasma system consisting of cold and hot electrons and hot ions using the Sagdeev pseudo-potential technique. The analysis is based on fluid equations and the Poisson equation. Solitary wave solutions are found when the Mach numbers exceed some critical values. The critical Mach numbers for the ion-acoustic solitons are found to be smaller than those for electron-acoustic solitons for a given set of plasma parameters. The critical Mach numbers of ion-acoustic solitons increase with the increase of hot electron temperature and the decrease of cold electron density. On the other hand, the critical Mach numbers of electron-acoustic solitons increase with the increase of the cold electron density as well as the hot electron temperature. The ion-acoustic solitons have positive potentials for the parameters considered. However, the electron-acoustic solitons have positive or negative potentials depending whether the fractional cold electron density with respect to the ion density is greater or less than a certain critical value. Further, the amplitudes of both the ion- and electron-acoustic solitons increase with the increase of the hot electron temperature. Possible application of this model to electrostatic solitary waves (ESWs) observed on the auroral field lines by Viking spacecraft is discussed

Study of nonlinear ion- and electron-acoustic waves in multi-component space plasmas

“…The nonlinear ion-acoustic waves in multi-species plasmas have been studied by several workers (Buti, 1980;Hudson et al, 1983;Qian et al, 1988;Bharutram and Shukla, 1986;Berthomier et al, 1998;Reddy and Lakhina, 1991;Reddy et al, 1992). The electronacoustic waves in multi-species plasmas have been discussed by Watanabe and Tanuti (1977); Gary and Tokar (1985); Hellberg (1985, 2001); Ashour-Abdalla and Okuda (1986); Pottelette et al (1990); Dubouloz et al (1991Dubouloz et al ( , 1993; Berthomier et al (2000Berthomier et al ( , 2003; ; Tagare et al (2004);Cattaert et al (2005), Kakad et al (2007) and Lakhina et al (2008).…”

“…Recently, Lakhina et al (2008) have studied a threecomponent plasma system consisting of cold and hot electrons and one type of ions. Solitary wave solutions were found when the Mach numbers exceed some critical values.…”

Response to “Comment on ‘Existence domains of slow and fast ion-acoustic solitons in two-ion space plasmas’” [Phys. Plasmas 23, 064701 (2016)]

“…One can recover Equation (7) 17). But both these forms of Sagdeev potential cannot handle a cold (T ¼ 0) plasma species, and are inferior to the expression of Sagdeev potential as given in a series of paper by Lakhina et al [10][11][12]15,16 which can handle cold as well as warm plasma species, but then here, one needs to keep track of proper signs for the density expressions for different plasma species.…”

“…[10][11][12][13] The idea of writing the Sagdeev potential with a unique sign for plasma species grew when we came across the work of Ghosh et al 14 who presented densities in a different way than given in our earlier papers. 15,16 Equation (6) in Ref. 1 is written in the form first given by Ghosh et al 14 If one considers the lower sign (i.e., minus sign) in this equation, and do the symbolic algebraic operation on the terms under the square root, all densities regain their equilibrium value when U ¼ 0.…”

Effects of hot electron inertia on electron-acoustic solitons and double layers

“…[25][26][27][28] Thus, even the species having the highest thermal speeds are assumed to behave adiabatically. Like the isothermal hot electron model, the adiabatic model takes account of the effects of finite hot electron inertia.…”