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Title: Nonlinear evolution of the magnetized Kelvin-Helmholtz instability: From fluid to kinetic modeling

The nonlinear evolution of collisionless plasmas is typically a multi-scale process, where the energy is injected at large, fluid scales and dissipated at small, kinetic scales. Accurately modelling the global evolution requires to take into account the main micro-scale physical processes of interest. This is why comparison of different plasma models is today an imperative task aiming at understanding cross-scale processes in plasmas. We report here the first comparative study of the evolution of a magnetized shear flow, through a variety of different plasma models by using magnetohydrodynamic (MHD), Hall-MHD, two-fluid, hybrid kinetic, and full kinetic codes. Kinetic relaxation effects are discussed to emphasize the need for kinetic equilibriums to study the dynamics of collisionless plasmas in non trivial configurations. Discrepancies between models are studied both in the linear and in the nonlinear regime of the magnetized Kelvin-Helmholtz instability, to highlight the effects of small scale processes on the nonlinear evolution of collisionless plasmas. We illustrate how the evolution of a magnetized shear flow depends on the relative orientation of the fluid vorticity with respect to the magnetic field direction during the linear evolution when kinetic effects are taken into account. Even if we found that small scale processes differmore » between the different models, we show that the feedback from small, kinetic scales to large, fluid scales is negligible in the nonlinear regime. This study shows that the kinetic modeling validates the use of a fluid approach at large scales, which encourages the development and use of fluid codes to study the nonlinear evolution of magnetized fluid flows, even in the collisionless regime.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ; ;  [1] ;  [1] ;  [2] ;  [4] ;  [5] ;  [6] ;  [7] ;
  1. Dipartimento di Fisica, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy)
  2. (France)
  3. (Germany)
  4. International Institute for Fusion Science/PIIM, UMR 7345 CNRS, Aix-Marseille University, 13397 Marseille (France)
  5. Astronomical Institute and Institute of Atmospheric Physics, AS CR Bocni II/1401, CZ-14131 Prague, Czech Republic and Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 11519 Prague (Czech Republic)
  6. Space Sciences Laboratory, University of California Berkeley, 7 Gauss Way, Berkeley, California 94720, USA and Astronomical Institute and Institute of Atmospheric Physics, AS CR Bocni II/1401, CZ-14131 Prague (Czech Republic)
  7. Astronomical Institute and Institute of Atmospheric Physics, AS CR Bocni II/1401, CZ-14131 Prague (Czech Republic)
Publication Date:
OSTI Identifier:
22218510
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 10; 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; COLLISIONLESS PLASMA; COMPARATIVE EVALUATIONS; FLUID FLOW; HELMHOLTZ INSTABILITY; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; NONLINEAR PROBLEMS; PLASMA SIMULATION; RELAXATION; SHEAR; VORTICES