Experimental Analysis and Numerical Simulation of the Operation of the DEMETER Electric Field Instrument in Deep Equatorial Plasma Depletions

The development of deep plasma depletions in the equatorial ionosphere at time of magnetic storms is of particular interest in space and plasma physics as well as in the field of radio communications. Detailed plasma, dc electric field, and wave observations were performed by the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions microsatellite through several depletions where the large Debye length may lead to significant disturbances on the measurements of dc electric fields by the double probe instrument. After an overview of the data acquired in a well-developed plasma cavity, we present a numerical simulation study that was undertaken to model the operation of the electric field probes in their actual environment. The initial results indicate that, in low-density ionospheric plasma and depending on the potential difference between the probes and the boom, non negligible errors may arise from the influence of the boom on the probe current collection.