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Title: Theory and simulations of electron vortices generated by magnetic pushing

Abstract

Vortex formation and propagation are observed in kinetic particle-in-cell (PIC) simulations of magnetic pushing in the plasma opening switch. These vortices are studied here within the electron-magnetohydrodynamic (EMHD) approximation using detailed analytical modeling. PIC simulations of these vortices have also been performed. Strong v×B forces in the vortices give rise to significant charge separation, which necessitates the use of the EMHD approximation in which ions are fixed and the electrons are treated as a fluid. A semi-analytic model of the vortex structure is derived, and then used as an initial condition for PIC simulations. Density-gradient-dependent vortex propagation is then examined using a series of PIC simulations. It is found that the vortex propagation speed is proportional to the Hall speed v{sub Hall}≡cB{sub 0}/4πn{sub e}eL{sub n}. When ions are allowed to move, PIC simulations show that the electric field in the vortex can accelerate plasma ions, which leads to dissipation of the vortex. This electric field contributes to the separation of ion species that has been observed to occur in pulsed-power experiments with a plasma-opening switch.

Authors:
; ; ;  [1];  [2]
  1. Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States)
  2. An Independent Consultant through ENGILITY, Chantilly, Virginia 20151 (United States)
Publication Date:
OSTI Identifier:
22227869
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 8; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; APPROXIMATIONS; ELECTRIC FIELDS; ELECTRONS; MAGNETOHYDRODYNAMICS; PLASMA DENSITY; PLASMA SIMULATION; PLASMA SWITCHES; PULSES; SHOCK WAVES; VORTICES

Citation Formats

Richardson, A. S., Angus, J. R., Swanekamp, S. B., Schumer, J. W., and Ottinger, P. F. Theory and simulations of electron vortices generated by magnetic pushing. United States: N. p., 2013. Web. doi:10.1063/1.4817746.
Richardson, A. S., Angus, J. R., Swanekamp, S. B., Schumer, J. W., & Ottinger, P. F. Theory and simulations of electron vortices generated by magnetic pushing. United States. doi:10.1063/1.4817746.
Richardson, A. S., Angus, J. R., Swanekamp, S. B., Schumer, J. W., and Ottinger, P. F. Thu . "Theory and simulations of electron vortices generated by magnetic pushing". United States. doi:10.1063/1.4817746.
@article{osti_22227869,
title = {Theory and simulations of electron vortices generated by magnetic pushing},
author = {Richardson, A. S. and Angus, J. R. and Swanekamp, S. B. and Schumer, J. W. and Ottinger, P. F.},
abstractNote = {Vortex formation and propagation are observed in kinetic particle-in-cell (PIC) simulations of magnetic pushing in the plasma opening switch. These vortices are studied here within the electron-magnetohydrodynamic (EMHD) approximation using detailed analytical modeling. PIC simulations of these vortices have also been performed. Strong v×B forces in the vortices give rise to significant charge separation, which necessitates the use of the EMHD approximation in which ions are fixed and the electrons are treated as a fluid. A semi-analytic model of the vortex structure is derived, and then used as an initial condition for PIC simulations. Density-gradient-dependent vortex propagation is then examined using a series of PIC simulations. It is found that the vortex propagation speed is proportional to the Hall speed v{sub Hall}≡cB{sub 0}/4πn{sub e}eL{sub n}. When ions are allowed to move, PIC simulations show that the electric field in the vortex can accelerate plasma ions, which leads to dissipation of the vortex. This electric field contributes to the separation of ion species that has been observed to occur in pulsed-power experiments with a plasma-opening switch.},
doi = {10.1063/1.4817746},
journal = {Physics of Plasmas},
number = 8,
volume = 20,
place = {United States},
year = {Thu Aug 15 00:00:00 EDT 2013},
month = {Thu Aug 15 00:00:00 EDT 2013}
}
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