Three Dimensional Equilibrium and Stability of Ionospheric Plasma Clouds
NAVAL RESEARCH LAB WASHINGTON DC
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The equilibrium and stability of three dimensional ionospheric plasma clouds is investigated. The equilibrium density profile is assumed to be a 3D waterbag with a circular cross-section transverse to B, and an ellipsoidal cross-section parallel to B. The equilibrium potential consists of two parts a polarization potential driven by a uniform neutral wind, and an ambipolar potential driven by parallel electron pressure. The latter potential is shown to cause sheared azimuthal plasma flows perpendicular to B. A stability analysis of this equilibrium is carried out. It is found that the E X B instability, which causes the structuring of ionospheric plasma clouds, can be stabilized by the azimuthal flow. A marginal stability criterion is derived. On the basis of this stability criteria, striations of barium clouds in the ionospheric F region should be stable to further bifurcation, as is observed. Keywords Barium clouds Ionospheric disturbances E x B instability.
- Atmospheric Physics