Nonlinear evolution of the electromagnetic electron-cyclotron instability in bi-Kappa distributed plasma

B. Eliasson, M. Lazar

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Abstract

This paper presents a numerical study of the linear and nonlinear evolution of the electromagnetic electron-cyclotron (EMEC) instability in a bi-Kappa distributed plasma. Distributions with high energy tails described by the Kappa power-laws are often observed in collision-less plasmas (e.g., solar wind, accelerators), where wave-particle interactions control the plasma thermodynamics and keep the particle distributions out of Maxwellian equilibrium. Under certain conditions, the anisotropic bi-Kappa distribution gives rise to plasma instabilities creating low-frequency EMEC waves in the whistler branch. The instability saturates nonlinearly by reducing the temperature anisotropy until marginal stability is reached. Numerical simulations of the Vlasov-Maxwell system of equations show excellent agreement with the growth-rate and real frequency of the unstable modes predicted by linear theory. The wave-amplitude of the EMEC waves at nonlinear saturation is consistent with magnetic trapping of the electrons.
Original languageEnglish
Article number062109
Number of pages9
JournalPhysics of Plasmas
Volume22
Issue number6
DOIs
Publication statusPublished - 15 Jun 2015

Keywords

  • electromagnetic electron-cyclotron instability
  • bi-Kappa distributed plasma
  • numerical simulations

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