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- The Electron Drift Instrument (EDI) on EQUATOR-S measures the displacement of a
weak (< 1 µA) beam of test electrons, after one gyration in the ambient
magnetic field, that is induced by electric fields or magnetic gradients. This
displacement causes the beam to return to a detector on the spacecraft only
when emitted in one of two precicely determined directions. By employing two
beams and two detectors, these directions can be monitored continuously and the
displacement obtained by triangulation. For small magnetic fields the
triangulation degenerates and the displacement is obtained instead from the
difference in the travel times of the electrons in the two beams. As a
by-product, the measured times-of-flight provide a precise measurement of the
magnetic field magnitude. To separately determine the electric fields and the
magnetic field gradients, the electron energy is varied between 1.0 and 0.5
keV. Time-resolution varies with ambient conditions, but should typically be
100 ms or better. The electron drift instrument on EQUATOR-S is identical to
the instrument developed for CLUSTER.
See:
http://www.mpe-garching.mpg.de/EQS/eq-s-instruments.html
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