Browsing by Author "Maharaj, Shimul Kumar"

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    On the role of high speed electron beams in the generation of subsonic solitons on electron dynamic timescales
    (American Institute of Physics, 2025) Bharuthram, Ramesh; Maharaj, Shimul Kumar
    A comprehensive theoretical investigation of the effects of electron beams on high frequency electron-acoustic waves is conducted for plasmas comprising two warm (adiabatic) electron components, Boltzmann electrons, and immobile ions of which one or both adiabatic electron fluid components are modeled as drifting (beams). A systematic approach is followed, starting with a single beam model comprising cool electrons, warm beam electrons, and hot electrons consistent with Berthomier et al. [Phys. Plasmas 7, 2987–2994 (2000)] and then proceeding to models with asymmetric and symmetric counterstreaming electron beams. The subsonic character of the solitons in the nonlinear regime is attributed to the effect of the beam(s) that support(s) the directional change of the backward propagating fast (or both slow mode) waves in the model with a single (counterstreaming) beam(s). This results in the coupling of two wave modes, which decouple for higher beam speeds. The results of our study are generic to other plasma systems containing heavier inertial plasma components as the findings are very similar to ion beam effects on low frequency ion-acoustic waves reported by Zank and McKenzie [J. Plasma Phys. 39, 183–191 (1988)] and Lakhina et al. [Phys. Scr. 95, 105601 (2020)] in models with a single and counterstreaming ion beams, respectively. In fact, similar reasoning applies in validating the generation of subsonic waves in the above reports as it relates to the directional change(s) of the linear wave(s), which also explains the generation of subsonic waves in the paper by Berthomier and coworkers in a single beam model.