OBSERVATION AND THEORY OF TOPSIDE IONOSPHERIC PLASMA INHOMOGENEITIES

In the rocket experiment ''Vertical-10'', a spectrum analyser of plasm a irregularities and a Langmuir probe were used. A large-scale plasma inhomogeneity decay into small-scale structure was observed in the nig httime topside ionosphere over a broad band of irregular sizes from so me tens of metres to several hundreds of kilometres. We suppose that i nternal gravity wave damping at altitudes 300-500 km heats the upper i onosphere and, due to superthermal charged particle fluxes, large-scal e plasma inhomogeneities can be induced. A large-scale, electrostatica lly unstable plasma inhomogeneity which decays into small-scale struct ure was observed in our experiment. The experimental results, an analy tical calculation and some computations are presented for the treatmen t of possible mechanisms for plasma inhomogeneity generation and decay . (C) 1998 Elsevier Science Ltd. All rights reserved.