Oxygen cyclotron harmonic waves in the deep plasmasphere during magnetic storms

O A Pokhotelov , D O Pokhotelov , F. Z. Feygin , V. Gladychev , Michel Parrot (1) , K. Hayashi , J. Kangas , K. Mursula

1 LPCE - Laboratoire de physique et chimie de l'environnement

A new approach to the generation of storm-associated ULF waves with discrete spectra (ion cyclotron harmonic waves) observed in the equatorial plasmasphere is presented. It is proposed that the appearance of waves with phase velocities smaller than the Alfv6n velocity is connected with a strong dispersion of magnetosonic waves near the hi-ion frequency occurring in the presence of oxygen ions of ionospheric origin. The waves are generated by an instability involving hot oxygen ions with loss cone or ring like distributions. Such ions are found in the magnetosphere during magnetic storms. A simple analytical model of this instability is elaborated. It is shown that ULF wave observations on board Akebono satellite are in a reasonable agreement with the present theoretical approach.

Domaines: Planète et Univers [physics]

O A Pokhotelov, D O Pokhotelov, F. Z. Feygin, V. Gladychev, Michel Parrot, et al.. Oxygen cyclotron harmonic waves in the deep plasmasphere during magnetic storms. Journal of Geophysical Research Space Physics, 1997, 102, pp.77-83. ⟨insu-03235174⟩