Electron Signatures and Alfven Waves



  • The electron signatures which appear together with Alfven waves observed by the Freja satellite in the auroral region are reported. Precipitating electrons are detected both with and just before the wave. The observed Alfven waves must therefore be capable of accelerating electrons to higher energies than the local phase velocity of these waves in order for the electrons to move in advance of the wave. The characteristics of such electrons suggest electrons moving infront of the wave have characteristics of origin from warmer and lower density plasma while the electrons moving with the wave have characteristics of cooler and denser plasma. The pitch angle distribution of the electrons moving with the wave indicates that there is continuous acceleration of new particles by the wave, i.e. a propagating Alfven wave is the source of these electrons . A simple model of a propagating source is made to model the electrons that are moving in advance of the wave. Depending on whether accelerated electrons leave the wave above or below the altitude where the Alfven wave has the highest phase velocity, the detected electron signatures will be different; electron dispersion or potential drop like, respectively. It is shown that the Alfven wave acceleration can create electron signatures similar to inverted-V structures.
  • Authors

  • Andersson, Laila
  • Ivchenko, N
  • Clemmons, James
  • Namgaladze, AA
  • Gustavsson, B
  • Wahlund, J-E
  • Eliasson, L
  • Yuik, RY
  • Publication Date

  • 2000
  • International Standard Book Number (isbn) 10

  • 9171919147
  • International Standard Book Number (isbn) 13

  • 9789171919144