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Auroral Acceleration and Radiation

  • R. Pottelette
  • R.A. Treumann
Part of the Lecture Notes in Physics book series (LNP, volume 687)

Abstract

A brief review is given of the recent achievements in understanding the connection between processes in the generation of auroral acceleration and processes taking place at the tailward reconnection site. It is shown that most of the acceleration in the aurora is due to local field-aligned electric potentials which are located in vertically narrow double layers along the magnetic field of the order of ~10 km and which are the site of preferential excitation of phase space holes of kilometer size extension along the magnetic field which by themselves sometimes represent local potential drops and accelerate electrons and ions antiparallel to each other such that the energy modulation of the electron and ion energy fluxes are in antiphase. Auroral kilometric radiation observations suggest that these structures may be the elementary radiation sources which build up the entire spectrum of the auroral kilometric radiation. Leaving open the very generation mechanism of the double layer whether produced by locally applied shear flows as recently suggested in the literature (and reviewed here as well) we argue that the field aligned current generator responsible for the production of the initial auroral current system is non-local but is related to reconnection in the tail. The field aligned currents are interpreted as the closure currents required to close the recently observed electron Hall current system in the ion diffusion region at the tail reconnection site. Such a model is very attractive as it does not need any other secondary current disruption mechanism. Coupling to the ionosphere may be provided by kinetic Alfvén waves emanating from the Hall reconnection region as surface waves and generating local shear flow when focussing close to the ionosphere and transforming into shear-kinetic Alfvén waves. A main problem still remains in how the decoupling of the two hemispheres observed in the aurora is produced at reconnection site. Multiple reconnection would be one possible solution.

Keywords

Double Layer Current Sheet Electron Hole Auroral Region Reconnection Site 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer 2006

Authors and Affiliations

  • R. Pottelette
    • 1
  • R.A. Treumann
    • 1
    • 2
  1. 1.CETP/CNRS, 4 av. de NeptuneFrance
  2. 2.Ludwig-Maximilians Universität München, Sektion GeophysikMünchenGermany

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