Alternative ion-acoustic solitary waves in magnetized low beta plasma consisting of warm adiabatic ions, nonthermal electrons, and electrons having a vortexlike distribution

Abstract

The solitary wave structures of the ion-acoustic waves propagating obliquely to an external uniform magnetic field have been considered in a low beta plasma consisting of warm adiabatic ions, nonthermal electrons, due to Cairns et al. [Geophys. Res. Lett. 22, 2709 (1995)], which generates the fast energetic electrons and electrons having a vortexlike distribution, due to Schamel [Plasma Phys. 13, 491 (1971); 14, 905 (1972)], taking care of both free and trapped electrons, immersed in a uniform static magnetic field. The nonlinear dynamics of ion-acoustic waves in such a plasma is shown to be governed by Schamel’s modified Korteweg–de Vries–Zakharov–Kuznetsov equation. When the coefficient of the nonlinear term of this equation vanishes, the vortexlike velocity distribution function of electrons simply becomes the isothermal velocity distribution function of electrons and the nonlinear behavior of the same ion-acoustic wave is described by a Korteweg–de Vries–Zakharov–Kuznetsov (KdV-ZK) equation. A combined Schamel’s modified Korteweg–de Vries–Zakharov–Kuznetsov (S-KdV-ZK) equation is shown to describe the nonlinear behavior of ion-acoustic wave when the vortexlike velocity distribution function of electrons approaches the isothermal velocity distribution function of electrons, i.e., when the contribution of trapped electrons tends to zero. This combined S-KdV-ZK equation admits an alternative solitary wave solution having profile different from sech4 or sech2. The condition for the existence of this alternative solitary wave solution has been obtained. It is found that this alternative solitary wave solution approaches the solitary wave solution (sech2-profile) of the KdV-ZK equation when the contribution of trapped electrons tends to zero.

Ion acoustic solitary waves in magneto-rotating plasmas

“…If the length scales are the same in both parallel and perpendicular directions to the external magnetic field and if the characteristic time is very much greater than the electron Larmor period, then the electrons move essentially along the magnetic field [34] and it is assumed that the phase velocity of wave is much smaller than the electron thermal velocity, due to which the isothermality of the plasma is expressed through electron density in the form of a Boltzmann relation as…”

Linear and nonlinear obliquely propagating ion-acoustic waves in magnetized negative ion plasma with non-thermal electrons

“…Under these conditions the electrons move essentially along the magnetic field (Islam et al 2009). Therefore, the electron density for energetic electrons following Cairn's distribution is given by Cairns et al (1996) and ElLabany et al (2010) as…”

“…Further, we assume that the characteristic time is very much larger than the electron Larmour period, and length scales are the same in both parallel and perpendicular directions to the magnetic field. Under these conditions the electrons move essentially along the magnetic field (Islam et al 2009). Therefore, the electron density for energetic electrons following Cairn's distribution is given by Cairns et al (1996) and El-Labany et al (2010) as…”

Ion-acoustic double layers in a magnetized low-beta plasma consisting of warm adiabatic ions, non-thermal electrons and electrons with a vortex-like distribution

“…The model of the velocity distribution function of non-thermal electrons was considered for the first time by Cairns et al [2] for the study of ion-acoustic solitary structures in the presence of a population of fast energetic electrons together with a population of Maxwellian distributed electrons. This type of velocity distribution has been termed as non-thermal distribution and was considered by many authors in various studies of different collective processes in plasmas and dusty plasmas [3,20,21,[29][30][31][32][33][34][35][36][37][38].…”

“…Very recently, Islam et al [38] extended the work of Bandyopadhyay and Das [30], taking a superposition of non-thermal electrons and electrons having a vortex-like distribution whose number densities are, respectively, given by…”