ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-20-1499-2002 Electron acceleration observed by the FAST satellite within the IAR during a 3 Hz modulated EISCAT heater experiment Cash S. R. 1 3 Davies J. A. 1 Kolesnikova E. 1 Robinson T. R. 1 Wright D. M. 1 Yeoman T. K. 1 Strangeway R. J. 2 Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK University 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) 30 09 2002 20 9 1499 1507 Copyright: © 2002 S. R. Cash et al. 2002 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/20/1499/2002/angeo-20-1499-2002.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/20/1499/2002/angeo-20-1499-2002.pdf

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.<br><br><b>Key words. </b>Ionosphere (active experiments; particle acceleration) – Magnetospheric physics (electric fields)