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Ann. Geophys., 19, 1273-1288, 2001 www.ann-geophys.net/19/1273/2001/ © European Geosciences Union 2001
The Electron Drift Instrument on Cluster: overview of first results
G. Paschmann1, J. M. Quinn2, R. B. Torbert2, H. Vaith1, C. E. McIlwain3, G. Haerendel4, O. H. Bauer1, T. Bauer1, W. Baumjohann5, W. Fillius3, M. Förster1, S. Frey1, E. Georgescu1, S. S. Kerr3, C. A. Kletzing6, H. Matsui2, P. Puhl-Quinn1, and E. C. Whipple7 1Max-Planck-Institut für extraterrestrische Physik, 85748 Garching, Germany 2University of New Hampshire, Durham, NH 03824, USA 3University of California at San Diego, La Jolla, CA 92093, USA 4International University Bremen, 28725 Bremen, Germany 5Space Research Institute, 8042 Graz, Austria 6University of Iowa, Iowa City, IA 52242, USA 7University of Washington, Seattle, WA 98195, USA
Abstract. EDI measures the drift
velocity of artificially injected electron beams. From this drift velocity, the
perpendicular electric field and the local magnetic field gradients can be
deduced when employing different electron energies. The technique requires the
injection of two electron beams at right angles to the magnetic field and the
search for those directions within the plane that return the beams to their
associated detectors after one or more gyrations. The drift velocity is then
derived from the directions of the two beams and/or from the difference in
their times-of-flight, measured via amplitude-modulation and coding of the
emitted electron beams and correlation with the signal from the returning
electrons. After careful adjustment of the control parameters, the beam
recognition algorithms, and the onboard magnetometer calibrations during the
commissioning phase, EDI is providing excellent data over a wide range of
conditions. In this paper, we present first results in a variety of regions
ranging from the polar cap, across the magnetopause, and well into the
magnetosheath.
Key words. Electron drift velocity
(electric fields; plasma convection; instruments and techniques)
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