Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.490 IF 1.490
  • IF 5-year value: 1.445 IF 5-year
    1.445
  • CiteScore value: 2.9 CiteScore
    2.9
  • SNIP value: 0.789 SNIP 0.789
  • IPP value: 1.48 IPP 1.48
  • SJR value: 0.74 SJR 0.74
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 88 Scimago H
    index 88
  • h5-index value: 21 h5-index 21
Volume 22, issue 3
Ann. Geophys., 22, 1053–1060, 2004
https://doi.org/10.5194/angeo-22-1053-2004
© Author(s) 2004. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 22, 1053–1060, 2004
https://doi.org/10.5194/angeo-22-1053-2004
© Author(s) 2004. This work is distributed under
the Creative Commons Attribution 3.0 License.

  19 Mar 2004

19 Mar 2004

The spatio-temporal structure of impulse-generated azimuthalsmall-scale Alfvén waves interacting with high-energy chargedparticles in the magnetosphere

D. Yu. Klimushkin and P. N. Mager D. Yu. Klimushkin and P. N. Mager
  • Institute of Solar-Terrestrial Physics (ISTP), Russian Academy of Science, Siberian Branch, Irkutsk, P.O.Box 4026, 664033, Russia

Abstract. It is assumed to date that the energy source of azimuthal small-scale ULF waves in the magnetosphere (azimuthal wave numbers m≧1) is provided by the energetic particles interacting with the waves through the bounce-drift resonance. In this paper we have solved the problem of the bounce-drift instability influence on the spatio-temporal structure of Alfvén waves excited by a source of the type of sudden impulse in a dipole-like magnetosphere. It is shown that the impulse-generated Alfvén oscillation within a time τ~m∕ΩTN (where ΩTN is the toroidal eigenfrequency) is a poloidal one, and each field line oscillates with its own eigenfrequency that coincides with the poloidal frequency of a given L-shell. As time elapses, the wave becomes toroidally polarized because of the phase difference of the disturbance, and the oscillation frequency of field lines tends to the toroidal frequency. The drift-bounce instability growth rate becomes smaller during the wave temporal evolution, and the instability undergoes stabilization when the wave frequency coincides with the toroidal eigenfrequency. The total amplification of the wave can be estimated as $e^{tilde{gamma}tau}$, where $tilde{gamma}$ is the wave growth rate at the beginning of the process, when it has its maximum value. The wave amplitude can increase only within a time ~τ, when it is poloidally polarized. After this time, when the wave becomes to be toroidally polarized, it goes damped because of the finite ionospheric conductivity. This is in qualitative agreement with the recent radar experimental data.

Key words. Magnetospheric physics (MHD waves and instabilities). Space plasma physics (kinetic and MHD theory; wave-particle interactions)

Publications Copernicus
Download
Citation