A New Theory of Sources of Birkeland Currents

  1. Thomas A. Potemra
  1. K. D. Cole

Published Online: 21 MAR 2013

DOI: 10.1029/GM028p0223

Magnetospheric Currents

Magnetospheric Currents

How to Cite

Cole, K. D. (1984) A New Theory of Sources of Birkeland Currents, in Magnetospheric Currents (ed T. A. Potemra), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM028p0223

Author Information

  1. NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771

Publication History

  1. Published Online: 21 MAR 2013
  2. Published Print: 1 JAN 1984

ISBN Information

Print ISBN: 9780875900551

Online ISBN: 9781118664131



  • Magnetospheric currents—Congresses;
  • Plasma instabilities—Congresses


A new approach to collisionless plasma (Cole 1983) shows the existence of current orthogonal to B along the low latitude boundary layer of the magnetosphere driven by electric field which is orthogonal to both B and the layer. In this case the relationship $${\rm p}_ \bot + {{{\rm B}ˆ{\rm 2} } \over {8_{\rm \pi } }} – {{{\rm \varepsilon E}_ \bot ˆ{\rm 2} } \over {8_{\rm \pi } }} = {\rm constant,} $$ holds on a line orthogonal to B and the layer, where ϵ is the dielectric constant of the plasma for electric fields orthogonal to B. Across the geomagnetic tail there flows a current in the direction of the dawn-dusk electric field, and in this case a relationship $${\rm p}_ \bot + {{{\rm B}ˆ{\rm 2} } \over {8_{\rm \pi } }} – {{{\rm \varepsilon E}_ \bot ˆ{\rm 2} } \over {8_{\rm \pi } }} = {\rm constant,} $$ holds along a line orthogonal to E and B. Divergence of both these currents is shown to be a source of Birkeland currents. Also some of the boundary layer current is continuous with current across the tail. Electric currents of physically similar origin flow in interplanetary space, and when the magnetosphere interrupts them, additional Birkeland currents are driven.