The electron energy distribution during HF pumping, a picture painted with all colors

B. Gustavsson (1) , T. Sergienko (2) , M. J. Kosch (3) , M. T. Rietveld (4) , B. U. E. Brändström (2) , T. B. Leyser (2) , B. Isham (5) , P. Gallop (6) , T. Aso (1) , M. Ejiri (1) , T. Grydeland (7) , Å. Steen (8) , C. Lahoz (7) , K. Kaila (9) , J. Jussila (9) , H. Holma (9)

1 NiPR - National Institute of Polar Research [Tokyo]
2 IRF - Swedish Institute of Space Physics [Kiruna]
3 Department of Communication Systems
4 EISCAT Scientific Association [Norway]
5 EISCAT Scientific Association
6 RAL - STFC Rutherford Appleton Laboratory
7 Dept. of Physics
8 Remspace Inc.
9 Oulo University

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, f_e(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

Domaines: Océan, Atmosphère; Sciences de la Terre

B. Gustavsson, T. Sergienko, M. J. Kosch, M. T. Rietveld, B. U. E. Brändström, et al.. The electron energy distribution during HF pumping, a picture painted with all colors. Annales Geophysicae, 2005, 23 (5), pp.1747-1754. ⟨hal-00317825⟩