Electron density and electric field fluctuations associated with developing plasma bubbles

Abstract

In situ measurements of the height variation of the ionospheric electric field and electron density were made on 18 December, 1995 at 2117 h (LT) from the equatorial station Alcantara (2.31° S; 44.4° W) in Brazil, with a rocket-borne electric field double probe and two different types of electron density probes. The main objective of the experiment was to study the characteristic features of the electron density and electric field fluctuations associated with plasma bubbles. The rocket reached an apogee altitude of 557 km covering a horizontal range of 589 km . The upleg electron density profile showed the presence of a clearly defined base for the F-region around 300 km , while the downleg profile showed the presence of a wide spectrum of electric field and electron density irregularities in the entire F-region. Spectral analysis of the fluctuations in the electron density and the electric field clearly indicated the presence of sharp spectral peaks associated to each other at several heights. This is suggestive of the electrostatic nature of these E-field waves with associated plasma density fluctuations. These waves seem to extend over hundreds of kilometres in the horizontal and vertical directions. The sources of these waves are not well understood, however.