The Generation of Ion-Conics Via Quasi-Linear Diffusion

  1. S.-I. Akasofu and
  2. J.R. Kan
  1. P. B. Dusenbery and
  2. L. R. Lyons

Published Online: 26 MAR 2013

DOI: 10.1029/GM025p0456

Physics of Auroral Arc Formation

Physics of Auroral Arc Formation

How to Cite

Dusenbery, P. B. and Lyons, L. R. (1981) The Generation of Ion-Conics Via Quasi-Linear Diffusion, in Physics of Auroral Arc Formation (eds S.-I. Akasofu and J.R. Kan), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM025p0456

Author Information

  1. Space Environment Laboratory, NOAA, ERL, Boulder, Colorado 80303

Publication History

  1. Published Online: 26 MAR 2013
  2. Published Print: 1 JAN 1981

ISBN Information

Print ISBN: 9780875900506

Online ISBN: 9781118664360

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Keywords:

  • Auroras—Addresses, essays, lectures

Summary

Downward currents in auroral regions are commonly measured with amplitudes of 1–5 μA/m2. Such currents are likely the result of upgoing thermal ionospheric electrons falling through a field-aligned potential drop on the order of their thermal energy. Similar distributions of upgoing ionospheric electrons may also occur in regions of diffuse auroral electron precipitation to preserve current continuity in the presence of the loss of the precipitating electrons to the ionosphere. The drift velocity of the upgoing electrons is sufficient to excite electrostatic ion cyclotron waves. In addition to being in Landau resonance with the upgoing electrons, these waves cyclotron resonate with the upgoing thermal ions with a parallel energy of several eV. Calculated quasilinear diffusion rates using measured wave spectra indicate that resonant ions can be heated to perpendicular energies on the order of 100 times the initial ion thermal energy. The results imply that conic distributions should not occur simultaneously with the keV electron precipitation associated with discrete arcs in regions of upward current but should occur in regions of upgoing ionospheric electrons which may include regions of downward current near the edges of auroral arcs and regions of diffuse auroral electron precipitation.