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Title: Nonlinear evolution of a strongly sheared cross-field plasma flow

Abstract

A study is presented of the nonlinear evolution of a magnetized plasma in which a localized electron cross-field flow is present. The peak velocity of the flow is denoted by [ital V][sub 0]; [ital L][sub [ital E]] represents the flow's shear scale length; and the regime [rho][sub [ital e]][lt][ital L][sub [ital E]][lt][rho][sub [ital i]] is considered, where [rho][sub [ital i]] and [rho][sub [ital e]] denote the ion and electron Larmor radii, respectively. It is shown that if the shear frequency [omega][sub [ital s]]=[ital V][sub 0]/[ital L][sub [ital E]] is larger than the lower-hybrid frequency, [omega][sub LH], then the system dynamics is dominated by the onset of the electron--ion-hybrid (EIH) mode which leads to the formation of coherent (vortexlike) structures in the electrostatic potential of the ensuing lower-hybrid waves. The wavelength of these structures is on the order of [ital L][sub [ital E]], and correlates well with that predicted by the linear theory of the EIH mode. Since the characteristic wavelength is longer than [rho][sub [ital e]], the corresponding phase velocity is low enough that there results significant direct resonant ion acceleration perpendicular to the confining magnetic field. When [omega][sub [ital s]][gt]3[omega][sub LH], the system exhibits significant anomalous viscosity (typically anmore » order of magnitude larger than that due to Coulomb collisions), which increases as the shear frequency is increased. As [omega][sub [ital s]] is reduced below [omega][sub LH], shear effects are no longer dominant and a smooth transition takes place in which the system dynamics is governed by the short wavelength (on the order of [rho][sub [ital e]]) lower-hybrid drift instability.« less

Authors:
;  [1]
  1. Space Plasma Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)
Publication Date:
OSTI Identifier:
6022302
Resource Type:
Journal Article
Journal Name:
Physics of Fluids B; (United States)
Additional Journal Information:
Journal Volume: 5:9; Journal ID: ISSN 0899-8221
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DRIFT INSTABILITY; PLASMA SIMULATION; EARTH MAGNETOSPHERE; LARMOR RADIUS; LASER-PRODUCED PLASMA; MAGNETOPAUSE; VISCOSITY; EARTH ATMOSPHERE; INSTABILITY; PLASMA; PLASMA INSTABILITY; PLASMA MICROINSTABILITIES; SIMULATION; 700340* - Plasma Waves, Oscillations, & Instabilities- (1992-)

Citation Formats

Romero, H, and Ganguli, G. Nonlinear evolution of a strongly sheared cross-field plasma flow. United States: N. p., 1993. Web. doi:10.1063/1.860653.
Romero, H, & Ganguli, G. Nonlinear evolution of a strongly sheared cross-field plasma flow. United States. https://doi.org/10.1063/1.860653
Romero, H, and Ganguli, G. 1993. "Nonlinear evolution of a strongly sheared cross-field plasma flow". United States. https://doi.org/10.1063/1.860653.
@article{osti_6022302,
title = {Nonlinear evolution of a strongly sheared cross-field plasma flow},
author = {Romero, H and Ganguli, G},
abstractNote = {A study is presented of the nonlinear evolution of a magnetized plasma in which a localized electron cross-field flow is present. The peak velocity of the flow is denoted by [ital V][sub 0]; [ital L][sub [ital E]] represents the flow's shear scale length; and the regime [rho][sub [ital e]][lt][ital L][sub [ital E]][lt][rho][sub [ital i]] is considered, where [rho][sub [ital i]] and [rho][sub [ital e]] denote the ion and electron Larmor radii, respectively. It is shown that if the shear frequency [omega][sub [ital s]]=[ital V][sub 0]/[ital L][sub [ital E]] is larger than the lower-hybrid frequency, [omega][sub LH], then the system dynamics is dominated by the onset of the electron--ion-hybrid (EIH) mode which leads to the formation of coherent (vortexlike) structures in the electrostatic potential of the ensuing lower-hybrid waves. The wavelength of these structures is on the order of [ital L][sub [ital E]], and correlates well with that predicted by the linear theory of the EIH mode. Since the characteristic wavelength is longer than [rho][sub [ital e]], the corresponding phase velocity is low enough that there results significant direct resonant ion acceleration perpendicular to the confining magnetic field. When [omega][sub [ital s]][gt]3[omega][sub LH], the system exhibits significant anomalous viscosity (typically an order of magnitude larger than that due to Coulomb collisions), which increases as the shear frequency is increased. As [omega][sub [ital s]] is reduced below [omega][sub LH], shear effects are no longer dominant and a smooth transition takes place in which the system dynamics is governed by the short wavelength (on the order of [rho][sub [ital e]]) lower-hybrid drift instability.},
doi = {10.1063/1.860653},
url = {https://www.osti.gov/biblio/6022302}, journal = {Physics of Fluids B; (United States)},
issn = {0899-8221},
number = ,
volume = 5:9,
place = {United States},
year = {Wed Sep 01 00:00:00 EDT 1993},
month = {Wed Sep 01 00:00:00 EDT 1993}
}