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Ann. Geophys., 21, 1073-1081, 2003
www.ann-geophys.net/21/1073/2003/
© European Geosciences Union 2003
Verification of the backward wave oscillator model of VLF chorus generation using data from MAGION 5 satellite
E. E. Titova1, B. V. Kozelov1, F. Jiriček2, J. Smilauer2, A. G. Demekhov3, and V. Yu. Trakhtengerts3
1Polar Geophysical Institute, Apatity, Russia
2Institute of Atmospheric Physics, Prague, Czech Republic
3Institute of Applied Physics, Nizhny Novgorod, Russia
Abstract. We present a detailed
study of chorus emissions in the magnetosphere detected on board Magion 5, when
the satellite was not far from the magnetic equator. We determine the frequency
sweep rate of more than 8500 electromagnetic VLF chorus elements. These results
are compared with the backward wave oscillator (BWO) regime of chorus
generation. Comparison of the frequency sweep rate with the BWO model shows: (i)
There is a correlation between the frequency sweep rates and the chorus
amplitudes. The frequency sweep rate increases with chorus amplitude, in
accordance with expectations from the BWO model; (ii) The chorus growth rate,
estimated from the frequency sweep rate, is in accord with that inferred from
the BWO generation mechanism; (iii) The BWO regime of chorus generation ensures
the observed decrease in the frequency sweep rate of the chorus elements with
increasing L-shell.
Key words. Magnetospheric physics (VLF
emissions, energetic particles) – Space plasma physics (wave-particle
interactions)
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