The Generation of Ion-Conics Via Quasi-Linear Diffusion
- S.-I. Akasofu and
- J.R. Kan
Published Online: 26 MAR 2013
Copyright 1981 by the American Geophysical Union.
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
- Published Online: 26 MAR 2013
- Published Print: 1 JAN 1981
Print ISBN: 9780875900506
Online ISBN: 9781118664360
- Auroras—Addresses, essays, lectures
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.