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Ann. Geophys., 23, 1747-1754, 2005
www.ann-geophys.net/23/1747/2005/
© European Geosciences Union 2005
The electron energy distribution during HF pumping, a picture painted with all colors
B. Gustavsson1, T. Sergienko2, M. J. Kosch3, M. T. Rietveld4, B. U. E. Brändström2, T. B. Leyser5, B. Isham6, P. Gallop7, T. Aso1, M. Ejiri1, T. Grydeland8, Å. Steen9, C. LaHoz8, K. Kaila10, J. Jussila10, and H. Holma10
1National Institute of Polar Research, Tokyo, Japan
2Swedish Institute of Space Physics, Kiruna, Sweden
3Department of Communication Systems, Lancaster University, Lancaster, England, UK
4EISCAT, Ramfjordmoen, Norway
5Swedish Institute of Space Physics, Uppsala, Sweden
6EISCAT Scientific Association, Longyearbyen, Norway
7Rutherford Appleton Laboratory, UK
8Dept. of Physics, University of Tromsø, Tromsø, Norway
9Remspace Inc., Linköping, Sweden
10Oulo University, Oulu, Finland
Abstract. The shape of the electron energy distribution has long been a
central question in the field of high-frequency radio-induced
optical emission experiments. This report presents estimates of
the electron energy distribution function, fe(E), from 0 to
60 eV, based on optical multi-wavelength (6300, 5577, 8446,
4278Å) data and 930-MHz incoherent scatter radar
measurements of ion temperature, electron temperature and electron
concentration. According to our estimate, the electron energy
distribution has a depression at around 2 eV, probably caused
by electron excitation of vibrational states in N2, and a high
energy tail that is clearly supra-thermal. The temporal evolution of
the emissions indicates that the electron temperature still plays an
important role in providing electrons with energies close to
2 eV. At the higher energies the electron energy distribution has a
non-thermal tail.
Keywords. Active experiments; Ionosphere atmosphere interaction;
Ionospheric physics
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