Instability of the parallel electromagnetic modes in Kappa distributed plasmas – I. Electron whistler-cyclotron modes

Authors

  • M. Lazar,

    Corresponding author
    1. Research Department – Plasmas with Complex Interactions, Ruhr-Universität Bochum, D-44780 Bochum, Germany
    2. Center for Plasma Astrophysics, Celestijnenlaan 200B, 3001 Leuven, Belgium
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  • S. Poedts,

    Corresponding author
    1. Research Department – Plasmas with Complex Interactions, Ruhr-Universität Bochum, D-44780 Bochum, Germany
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  • R. Schlickeiser

    Corresponding author
    1. Research Department – Plasmas with Complex Interactions, Ruhr-Universität Bochum, D-44780 Bochum, Germany
    2. Institut für Theoretische Physik, Lehrstuhl IV: Weltraum-und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
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E-mail: mlazar@tp4.rub.de (ML); Stefaan.Poedts@wis.kuleuven.be (SP); rsch@tp4.rub.de (RS)

ABSTRACT

The electron cyclotron emissions represent a useful tool in the diagnostics of fusion plasmas and space plasma fluctuations. The instability which enhances the whistler-cyclotron modes is driven in the presence of an ambient regular magnetic field by an excess of transverse kinetic energy of plasma particles. Previous studies have modelled the anisotropic particles with a bi-Maxwellian or a bi-Kappa distribution function and found a suppression of this instability in the presence of suprathermal tails. Here, the anisotropic plasma is modelled with a product-bi-Kappa distribution, with the advantage that this distribution function enables the use of two different spectral indices in the main directions, κ≠κ, and permits further characterization of kappa populations and their excitations. The exact numerical values of the growth rates and the instability threshold are derived and contrasted with those for a simple bi-Kappa and a bi-Maxwellian, using plasma parameters and magnetic fields relevant for the solar and terrestrial environments.

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