Abstract
The IESP experiment implemented onboard the Interball auroral probe measures the six components (3B, 3E) of the waves in the ULF range: 0.1–10 Hz and from time to time 0–30 Hz. Two different kinds of waves have been observed in the auroral region at altitudes between 10 000 and 20 000 km: (1) electrostatic emissions which consist of quasi-monochromatic structures with frequencies above the oxygen gyrofrequency, superimposed on a wide band signal interpreted as a Doppler broadening, (2) electromagnetic wide band spectrum fluctuations. These emissions are interpreted as current-driven electromagnetic or electrostatic ion cyclotron waves. The electromagnetic/electrostatic character is controlled by the plasma parameter βi and by the O+ concentration.
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Perraut, S., Roux, A., Darrouzet, F. et al. ULF wave measurements onboard the Interball auroral probe. Annales Geophysicae 16, 1105–1116 (1998). https://doi.org/10.1007/s00585-998-1105-7
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DOI: https://doi.org/10.1007/s00585-998-1105-7