Convective Stabilization of Ionospheric Plasma Clouds.
Abstract
We derive a stability criteria for the large-scale structuring of ionospheric plasma clouds due to the E X B gradient drift instability. For the equilibrium we consider a cylindrical 2D waterbag clou aligned along a uniform magnetic field that is polarized by a neutral wind. We perform a stability analysis that allows three dimensional perturbations (in r, theta, and z), and consider both local and global modes. We find that when the parallel wavenumber k sub z exceeds a threshold value, exponentially growing global eigenmodes form which are localized on the 'backside' of the cloud. This is in contrast to the k sub z = 0 limit in which there are no exponential solutions. As k sub z is increased further, the unstable modes localize at a finite angle away from the backside; at a point where the diamagnetic propagation velocity (V sub d) balances the convective flow velocity of the background plasma around the cloud (V sub b). We find that the E X B gradient drift instability is stable when V sub d > V sub b so that the cloud is no longer susceptible to large-scale structuring. Keywords: Plasma clouds, Ionospheric disturbances, Gradient drift instability, Striation freezing.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 19, 1986
- Accession Number
- ADA166431
Entities
People
- J. F. Drake
- Joseph D. Huba
Organizations
- United States Naval Research Laboratory