Turbulent motion in an artificial plasma inhomogeneity released in the ionosphere

Abstract

Artificial barium plasmas released in the upper atmosphere are found to be turbulent. Since the plasma has mean field and density gradients transverse to the earth magnetic field, its spectrum possesses a production subrange, where the mean gradients supply energy to the turbulent motion. The nonlinearity provides a mode transfer across each spectrum, and the molecular diffusion by collisions leads to a dissipation of the energy in the spectrum. An analytical theory based on a repeated cascade has been developed by Tchen (1973). Since the mathematical foundation for the screening of ranks in the cascade, in the purpose of closing the turbulent hierarchy, has been elaborated in that theory, the basic physical foundation are emphasised of the transport processes and a comparison is made between experiments from the artificial plasma inhomogeneities released in the ionosphere and the theoretical result of finding a k-3 law over all subranges of the field spectrum, and of finding the power laws k-3, k-1 and k-5 in the production, inertia and dissipation subranges of the density spectrum, respectively. The comparison is favorable with the optical densitometry of the turbulent density fluctuations in the artificial plasma clouds experiments in the ionosphere.