Electron and Ion Acceleration by Strong Electrostatic Turbulence

  1. S.-I. Akasofu and
  2. J.R. Kan
  1. Robert L. Lysak

Published Online: 26 MAR 2013

DOI: 10.1029/GM025p0444

Physics of Auroral Arc Formation

Physics of Auroral Arc Formation

How to Cite

Lysak, R. L. (1981) Electron and Ion Acceleration by Strong Electrostatic Turbulence, in Physics of Auroral Arc Formation (eds S.-I. Akasofu and J.R. Kan), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM025p0444

Author Information

  1. Space Sciences Laboratory, University of California, Berkeley 94720

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

The presence of electrostatic turbulence on auroral field lines will cause particle orbits to deviate from adiabatic trajectories. In weak turbulence theory, the turbulence causes a diffusion in velocity space which is quadratic in the amplitude of the waves. When turbulence is strong, particle trapping effects which cause a first order change in the particle orbits become important. For waves observed on auroral field lines, ion trapping may be important and affect models of transverse ion acceleration. The strength of the electrostatic ion cyclotron turbulence observed in the auroral zone may be attributed to the large convective growth rate associated with this mode. These waves mey be destabilized by the enhancement in the field aligned current which is a result of the onset of a magnetospheric substorm. The increase in the field aligned current is associated with the passage of shear mode Alfvén waves betweeen the magnetosphere and ionosphere. When these Alfvén waves have a perpendicular wavelength comparable to the ion gyroradius, they carry a parallel electric field which can accelerate the plasma in the topside auroral ionosphere, destabilizing the electrostatic ion cyclotron mode. The anomalous transport effects associated with the ion cyclotron turbulence can cuase dissipation of the Alfvén wave, leading to an energization of the plasma and the establishment of a double layer on auroral field lines.