Field Aligned Currents Measured by Incoherent Scatter on Board the Spacelab

Abstract

The incoherent scatter technique has in recent years played an important role in the study of the ionosphere and the thermosphere. Used as a remote sensing experiment, this technique has made possible over the whole range of ionospheric heights, and at several very different latitudes from the equator to the auroral zone, the study of daily and seasonal variations of the bulk parameters of the neutral and ionized atmospheres. Used on board the Spacelab, with the corresponding energy and size limitations, an incoherent scatter radar cannot cover similar ranges in space and times. Our purpose is to show that, used in a different way, aiming at a quasi-in-situ measurement (only one or two kilometers away from the spacecraft), it could permit with a very satisfactory accuracy the mapping of a parameter which has not been studied in ground-based experiments: the bulk velocity of thermal electrons. Associated with a simultaneous measurement of bulk ion velocities, this gives access to the study of field-aligned charge transports, which is of strong geophysical interest at all latitudes.