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Ann. Geophys., 20, 1499-1507, 2002
www.ann-geophys.net/20/1499/2002/
© European Geosciences Union 2002
Electron acceleration observed by the FAST satellite within the IAR during a 3 Hz modulated EISCAT heater experiment
S. R. Cash1, J. A. Davies1, E. Kolesnikova1, T. R. Robinson1, D. M. Wright1, T. K. Yeoman1, and R. J. Strangeway2
1Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK
2University of California, Institute of Geophysics and Planetary Physics, 405 Hilgard Ave., Los Angeles CA 90095, USA
Correspondence to: S. R. Cash (srcash@ion.le.ac.uk)
Abstract. A quantitative analysis
is presented of the FAST satellite electric field and particle flux data during
an EISCAT heating experiment run on 8 October 1998. Radio frequency heating,
modulated at 3 Hz, launched ULF waves from the ionosphere into the lower
magnetosphere. The ULF waves were observed in FAST data and constituted the
first satellite detection of artificially excited Alfvénic ULF waves. The
downward electron flux data for this event contain the first observations of
electrons undergoing acceleration within the Ionospheric Alfvén Resonator (IAR)
due to parallel electric fields associated with an artificially stimulated
Alfvén wave. The time history and spectral content of the observed down-ward
electron fluxes is investigated by considering the effects of a localised
parallel electric field. Furthermore, it is demonstrated that a power law
electron energy distribution describes the time-variable observed fluxes better
than a Maxwellian distribution.
Key words. Ionosphere (active
experiments; particle acceleration) – Magnetospheric physics (electric
fields)
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