Influence of bounce resonance effects on the cyclotron wave instabilities in dipole magnetospheric plasmas with anisotropic temperatureReport as inadecuate

Influence of bounce resonance effects on the cyclotron wave instabilities in dipole magnetospheric plasmas with anisotropic temperature - Download this document for free, or read online. Document in PDF available to download.

1 LNCC - MCT - Laboratorio Nacional de Computação Cientifica Rio de Janeiro 2 UERJ - Universidade do Estado do Rio de Janeiro Rio de Janeiro

Abstract : In this paper, we derive the dispersion equations for field-aligned cyclotron waves in an axisymmetric dipole magnetospheric plasmas with both the bi-Maxwellian and bi-Lorentzian distribution functions. To evaluate the contribution of trapped particles to the transverse current density components the Vlasov equation is solved using a standard method of switching to new variables associated with conservation integrals; new time-like variable is introduced instead of the geomagnetic latitude angle to describe the bounce-motion of trapped particles along the geomagnetic field; the perturbed electric field and current density components are Fourier-decomposed over the length of the geomagnetic field lines. As a result, the transverse permittivity elements are expressed by summation of bounce-resonant terms including the double integration in velocity space, the resonant denominators, and the corresponding phase coefficients. Due to geomagnetic field nonuniformity, the wave-particle resonance conditions in magnetospheric plasmas are entirely different from ones in the straight magnetic field; the all spectrum of the electric field is present in the given current density harmonic; the left- and right-hand polarized waves are coupled. To have some analogy with the linear theory of cyclotron waves in the straight magnetic field, we assume that the n-th harmonic of the electric field gives the main contribution to the n-th harmonic of the current density, and the connection of the left- and right-hand polarized waves is small. In this case, the dispersion equations for cyclotron waves have the simplest form and are suitable to analyze the instabilities of both the electron- and ion-cyclotron waves accounting for the bounce resonance effects.

Keywords : trapped particles anisotropic temperature field-aligned cyclotron waves cyclotron and bounce resonances magnetospheric plasma dispersion equation

Author: Nikolay Grishanov - Marco Raupp - Abimael Loula - Joaquim Pereira Neto -



Related documents