Ion acoustic solitons, double layers and supersolitons in a collisionless unmagnetized plasma consisting of nonthermal electrons and isothermal positrons

Abstract

Employing the Sagdeev pseudo-potential technique the ion acoustic solitary structures have been investigated in an unmagnetized collisionless plasma consisting of adiabatic warm ions, nonthermal electrons and isothermal positrons. The qualitatively different compositional parameter spaces clearly indicate the existence domains of solitons and double layers with respect to any parameter of the present plasma system. The present system supports the negative potential double layer which always restricts the occurrence of negative potential solitons. The system also supports positive potential double layers when the ratio of the average thermal velocity of positrons to that of electrons is less than a critical value. However, there exists a parameter regime for which the positive potential double layer is unable to restrict the occurrence of positive potential solitary waves and in this region of the parameter space, there exist positive potential solitary waves after the formation of a positive potential double layer. Consequently, positive potential supersolitons have been observed. The nonthermality of electrons plays an important role in the formation of positive potential double layers as well as positive potential supersolitons. The formation of positive potential supersoliton is analysed with the help of phase portraits of the dynamical system corresponding to the ion acoustic solitary structures of the present plasma system.

Modulational instability of ion acoustic waves in a multi-species collisionless magnetized plasma consisting of nonthermal and isothermal electrons

“…On the other hand, for conventional soliton, it is simple to check that the differentiation of φ has only one maximum (minimum). This property has already been explained by Paul et al [11].…”

“…For low frequency IA waves (ω << ω c ), the linear dispersion relation of IA waves can be easily obtained from the equations (1), (11) and (12) and this dispersion relation is…”

“…Here M is normalized by c s . Therefore, transforming the equation (1) and each component of the momentum equation (11) in the wave frame, which is moving with a constant velocity M along a direction l xx + m yŷ + n zẑ , we get the following equations:…”

Positron superthermality effects on the solitonic, dissipative, periodic waveforms for M-Kadomstev-Petviashvili-plasma-equation

“…Also, the effect of excess index of superthermality on wave pictures of depressed soliton, shock wave, envelope excitation and strong dispersive wave have been discussed [8,[15][16][17]. On the other hand, careful theoretical studies display the wave propagations in several shapes of nonlinear wave kinds in fluid dynamics and different plasmas modes, which are recognized as blow up, solitons, damped form, rational, shocklikes, supernonlinear, periodic and explosive [18][19][20][21][22][23]. The superthermal index supports on the cylindrical dissipated excitations have been deliberated in superthermal dust fluids [20].…”