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The nonlinear solitary wave in a magnetized plasma with the combined effect of ion collision and trapped electrons distribution is investigated. Using the reductive perturbation technique, the damped modified Schamel–Zakarov–Kuznetsov nonlinear wave equation is derived and analyzed numerically. Solitary wave propagation through collisional plasma medium is analyzed for different parameters such as free to trapped electrons temperature ratio, collisional term, positive and negative ion density ratio and ion mass ratio. It is observed that the increase in free to trapped electron temperature ratio enhances the speed of the solitons toward its direction of propagation where we observed the formation of fast wave mode, and the whole analysis has been carried out for fast wave mode. While the collisional effect due to ions and neutral particles significantly reduces the amplitude. The findings of this work will be helpful in understanding trapped electrons effect in collisional plasmas, containing negative ions. [ABSTRACT FROM AUTHOR]

The dust–ion–acoustic (DIA) solitary wave (SW) propagation in a magnetized dusty plasma consisting of mobile positive and heavy negative ions, nonthermal electrons and positrons is presented. By using reductive perturbation technique, three dimensional Zakharov–Kuznetsov (Z–K) equation is derived and the solution is obtained by using the tan-hyperbolic method. Here, the dust grain charging process by plasma constituents is represented by the equation following orbital motion limited (OML) theory. The characteristics features of solitary wave amplitudes arising due to different plasma parameters such as ions mass ratio, nonthermal parameters of electrons and positrons, temperature ratio of electrons and positrons, ions density ratio, and dust density ratio are analyzed. In this analysis, the influence of nonthermal electrons on solitary wave amplitude variation is observed as more significant than that of nonthermal positrons. The findings of this work can be helpful in understanding D, E, and F regions of the Earth's ionosphere, its mesosphere region, solar photosphere, and Titan's ionosphere. [ABSTRACT FROM AUTHOR]

We studied the propagation of small-amplitude dust ion acoustic (DIA) solitary waves in four-component relativistic plasma comprised of nonthermal electrons, mobile positively charged ions, positron beam and negatively charged massive dust particles. By using the reductive perturbation method, the Korteweg–de-Vries (KdV) nonlinear wave equation is derived numerically. In this work, we have elucidated the role of energetic positron beam in the relativistic plasma and analyzed the existence region for ion-acoustic (IA) solitary wave formation. It is found that for certain plasma parameters, the propagation of both compressive and rarefactive solitary waves is possible. Here, the injecting streaming positron beam in plasma gives rise to the increase in the phase velocity (Mach number) and reaches up to the hypersonic regime of flow velocity. It is observed that the initial increase in relativistic factor of positron beam , as well as temperature ratio of the positron beam to electrons decrease the characteristic features (the amplitude) of the compressive solitary wave potential profiles. On the other hand, on increasing dust grain charge , positron beam concentration ratio as well as nonthermal electrons concentration result in enhancement of the amplitudes of IA solitary wave potential profiles. The findings of this work can be more helpful in understanding the Earth's upper atmosphere (Aurora region of the ionosphere) as well as the space plasmas. [ABSTRACT FROM AUTHOR]

A modified mode of plasma production in a double plasma device is presented and plasma parameters are controlled in this configuration. Here plasma is produced by applying a discharge voltage between the hot filaments in the source (cathode) and the target magnetic cage (anode) of the device. In this configuration, the hot electron emitting filaments are present only in the source and the magnetic cage of this is kept at a negative bias such that due to the repulsion of the cage bias, the primary electrons can go to the grounded target and produce plasma there. The plasma parameters can be controlled by varying the voltages applied to the source magnetic cage and the separation grid of the device. [ABSTRACT FROM AUTHOR]