A Plausible Hypothesis for Striation Freezing in Ionospheric Plasma Clouds.
Abstract
Ionospheric plasma cloud striation phenomena exhibit a persistence of kilometer scale size structures, i.e., a freezing. Beyond a certain point in time the striations drift in unison without further bifurcation. Recent theoretical and nonlinear numerical simulation studies using a one level, 2D plasma cloud model with cross field diffusion produced a U shaped curve for minimum striation scale size, i.e., a structure's stability against further bifurcation, as a function of cloud to background Pedersen conductivity ratio (M). The minimum of the U (occurring for M approx. = 4), with classical electron-ion collisions (diffusion), results in a minimum scale size L sub o approx. = 10-20m. Even with M = 30, the results produced L sub o = 50m, clearly are not the kilometer type scale sizes observed. On the other hand nonlinear numerical simulation studies using a two level, 2D model, without electron-ion collision induced diffusion, showed that high density cloud striations create, as time goes on, high density image striations beneath them in the background ionosphere. This effectively increases the Pedersen conductivity associated with the cloud striations. Knowing these two results and extrapolating the U shaped curve to higher M, yields L sub o approx. = 500m for M approx. = 300. Thus it is proposed that the second level (background ionosphere) effect of amplifying the conductivity in a striation, via image striations because the second level is compressible, could result in km size minimum scale sizes (non-bifurcation), as time goes on. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 18, 1981
- Accession Number
- ADA103027
Entities
People
- Michael J. Keskinen
- Sidney L. Ossakow
- Steven T.P. Zalesak
Organizations
- United States Naval Research Laboratory