Electron Drift Instrument for cluster Final report

The Electron Drift Instrument (EDI) was developed to measure electric fields on the Cluster Mission. EDI is based on sensing the displacement of the electron orbit that occurs after a gyration in the ambient magnetic field if an electric field is present. For this purpose, EDI employs two electron guns with fully steerable beam directions, and two sensitive detectors. If the two beams are steered such that they return to their detectores, then the displacement can be determined through triangulation. For strong electric or weak magnetic fields, the displacement becomes very large, and the triangulation inaccurate. For this case EDI also measures the flight time of the electrons in the two beams. Their difference is also a measure of the electric field, while their sum is a measure of the magnetic field. After the failure of the Ariane 5 launch vehicle in 1996, the Cluster mission is now delayed until 2000. But in the meantime, the EDI flight-spare model has been flown on the Equator-S satellite. The results have established the validity of the EDI technique. (orig.)Available from TIB Hannover: F99B303+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Bonn (Germany)DEGerman