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Title: Intermittent convective transport carried by propagating electromagnetic filamentary structures in nonuniformly magnetized plasma

Abstract

Drift-Alfven vortex filaments associated with electromagnetic turbulence were recently identified in reversed field pinch devices. Similar propagating filamentary structures were observed in the Earth magnetosheath, magnetospheric cusp and Saturn's magnetosheath by spacecrafts. The characteristics of these structures closely resemble those of the so-called mesoscale coherent structures, prevailing in fusion plasmas, known as 'blobs' and 'edge localized mode filaments' in the boundary region, and propagating avalanchelike events in the core region. In this paper the fundamental dynamics of drift-Alfven vortex filaments in a nonuniformly and strongly magnetized plasma are revisited. We systemize the Lagrangian-invariant-based method. Six Lagrangian invariants are employed to describe structure motion and the resultant convective transport, namely, magnetic flux, background magnetic energy, specific entropy, total energy, magnetic momentum, and angular momentum. The perpendicular vortex motions and the kinetic shear Alfven waves are coupled through the parallel current and Ampere's law, leading to field line bending. On the timescale of interchange motion tau{sub perpendicular}, a thermal expansion force in the direction of curvature radius of the magnetic field overcomes the resultant force of magnetic tension and push plasma filament to accelerate in the direction of curvature radius resulting from plasma inertial response, reacted to satisfy quasineutrality. During this processmore » the internal energy stored in the background pressure gradient is converted into the kinetic energy of convective motion and the magnetic energy of field line bending through reversible pressure-volume work as a result of the plasma compressibility in an inhomogeneous magnetic field. On the timescale of parallel acoustic response tau{sub ||}>>tau{sub perpendicular}, part of the filament's energy is transferred into the kinetic energy of parallel flow. On the dissipation timescale tau{sub d}>>tau{sub perpendicular}, the kinetic energy and magnetic energy are eventually dissipated, which is accompanied by entropy production, and in this process the structure loses its coherence, but it has already traveled a distance in the radial direction. In this way the propagating filamentary structures induce intermittent convective transports of particles, heat, and momentum across the magnetic field. It is suggested that the phenomena of profile consistency, or resilience, and the underlying anomalous pinch effects of particles, heat, and momentum in the fusion plasmas can be interpreted in terms of the ballistic motion of these solitary electromagnetic filamentary structures.« less

Authors:
 [1]; ; ;  [2];  [1];  [3]
  1. Euratom-UKAEA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)
  2. Association Euratom-Risoe DTU, DK-4000 Roskilde (Denmark)
  3. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)
Publication Date:
OSTI Identifier:
21347117
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 17; Journal Issue: 2; Other Information: DOI: 10.1063/1.3302535; (c) 2010 American Institute of Physics; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALFVEN WAVES; ANGULAR MOMENTUM; MAGNETOHYDRODYNAMICS; PLASMA; PLASMA FILAMENT; TURBULENCE; VORTICES; FLUID MECHANICS; HYDRODYNAMICS; HYDROMAGNETIC WAVES; MECHANICS

Citation Formats

Xu, G S, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, Naulin, V, Rasmussen, J Juul, Nielsen, A H, Fundamenski, W, and Wan, B N. Intermittent convective transport carried by propagating electromagnetic filamentary structures in nonuniformly magnetized plasma. United States: N. p., 2010. Web. doi:10.1063/1.3302535.
Xu, G S, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, Naulin, V, Rasmussen, J Juul, Nielsen, A H, Fundamenski, W, & Wan, B N. Intermittent convective transport carried by propagating electromagnetic filamentary structures in nonuniformly magnetized plasma. United States. doi:10.1063/1.3302535.
Xu, G S, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, Naulin, V, Rasmussen, J Juul, Nielsen, A H, Fundamenski, W, and Wan, B N. Mon . "Intermittent convective transport carried by propagating electromagnetic filamentary structures in nonuniformly magnetized plasma". United States. doi:10.1063/1.3302535.
@article{osti_21347117,
title = {Intermittent convective transport carried by propagating electromagnetic filamentary structures in nonuniformly magnetized plasma},
author = {Xu, G S and Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 and Naulin, V and Rasmussen, J Juul and Nielsen, A H and Fundamenski, W and Wan, B N},
abstractNote = {Drift-Alfven vortex filaments associated with electromagnetic turbulence were recently identified in reversed field pinch devices. Similar propagating filamentary structures were observed in the Earth magnetosheath, magnetospheric cusp and Saturn's magnetosheath by spacecrafts. The characteristics of these structures closely resemble those of the so-called mesoscale coherent structures, prevailing in fusion plasmas, known as 'blobs' and 'edge localized mode filaments' in the boundary region, and propagating avalanchelike events in the core region. In this paper the fundamental dynamics of drift-Alfven vortex filaments in a nonuniformly and strongly magnetized plasma are revisited. We systemize the Lagrangian-invariant-based method. Six Lagrangian invariants are employed to describe structure motion and the resultant convective transport, namely, magnetic flux, background magnetic energy, specific entropy, total energy, magnetic momentum, and angular momentum. The perpendicular vortex motions and the kinetic shear Alfven waves are coupled through the parallel current and Ampere's law, leading to field line bending. On the timescale of interchange motion tau{sub perpendicular}, a thermal expansion force in the direction of curvature radius of the magnetic field overcomes the resultant force of magnetic tension and push plasma filament to accelerate in the direction of curvature radius resulting from plasma inertial response, reacted to satisfy quasineutrality. During this process the internal energy stored in the background pressure gradient is converted into the kinetic energy of convective motion and the magnetic energy of field line bending through reversible pressure-volume work as a result of the plasma compressibility in an inhomogeneous magnetic field. On the timescale of parallel acoustic response tau{sub ||}>>tau{sub perpendicular}, part of the filament's energy is transferred into the kinetic energy of parallel flow. On the dissipation timescale tau{sub d}>>tau{sub perpendicular}, the kinetic energy and magnetic energy are eventually dissipated, which is accompanied by entropy production, and in this process the structure loses its coherence, but it has already traveled a distance in the radial direction. In this way the propagating filamentary structures induce intermittent convective transports of particles, heat, and momentum across the magnetic field. It is suggested that the phenomena of profile consistency, or resilience, and the underlying anomalous pinch effects of particles, heat, and momentum in the fusion plasmas can be interpreted in terms of the ballistic motion of these solitary electromagnetic filamentary structures.},
doi = {10.1063/1.3302535},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 2,
volume = 17,
place = {United States},
year = {2010},
month = {2}
}