Effect of Electronic Inertia on the Gravito-Electrostatic Sheath Structure Formation
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Effect of Electronic Inertia on the Gravito-Electrostatic Sheath Structure Formation1 H. P. Goutam and P. K. Karmakar* Department of Physics, Tezpur University, Tezpur, Assam, Napaam, 784028 India *e-mail: [email protected] Received April 2, 2017; in final form, July 2, 2017
Abstract—The gravito-electrostatic sheath (GES) model, previously proposed to address the fundamental issues on the surface emission mechanism of outfl owing solar plasma on the basis of plasma−wall interaction processes with inertialess electrons on both bounded and unbounded scales, is reformulated in the light of active electron inertial response amid geometrical curvature effects. We accordingly derive the electron population distribution law considering both weak electron inertia and geometrical curvature effects in a new analytic construct coupled with the GES structure equations in a closed form. The analysis shows that the GES characteristics and hence plasma outflow dynamics are noticeably affected because of electron inertia. As a consequence of the electron inertia inclusion in contrast with the previous GES formalism, it is found that the GES width gets reduced (–5%), the sheath boundary gets contracted (–7%), the net current density at the surface gets reduced (–25%), the GES potential enhances (+17%), the transonic horizon decreases (‒35%), self-gravity enhances (+2%), and so forth. The obtained results are in fair accord with the existing model predictions centered around both the earlier GES formalisms and standard fluid-kinetic predictions. DOI: 10.1134/S1063780X18030030
1. INTRODUCTION The Sun, its atmosphere, and involved plasma flow dynamics have been one of the long-standing problems in the astroplasma communities for the last few decades [1–7]. The most fundamental issue in this contextual direction has been the emission mechanism of the solar wind from the Sun and its high-speed acceleration processes beyond. A number of studies have been made to address such problems in the past. Both fluid model [2, 3] and kinetic model [4–7] approaches have successfully been adopted to understand the underlying basic physical insights responsible for the solar wind flow dynamics. It may be noted that, these models have however rarely addressed the surface emission mechanism of the solar wind and subsequent energization from the viewpoint of plasma surface−wall interaction processes. The basic mechanism of the subsonic solar wind emission, supersonic acceleration, and related problems have been addressed in a recently proposed plasma-based gravito-electrostatic sheath (GES) model [8, 9]. The plasma wall interaction-based GES model [8, 9] has been successful in explaining a number of fundamental issues of the bounded Sun, its unbounded atmosphere, and associated flow dynamics. It has employed the laboratory plasma−wall (nondiffused) interaction physics on the astrophysical spa1 The article is published in the original.
tial scale for the first time. Its main outcome is that the genesis of the supersonic solar wind plasma (SW
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