The Artificially Injected Charged Particles as a Tool for the Measurement of the Electric Field in the Magnetosphere
The knowledge of the electric field in the magnetosphere is essential to understand processes such as the magnetospheric convection or the acceleration of charged particles. But, contrary to the magnetic field which plays also an important role in this understanding, it is very difficult to measure it and especially its parallel component to the magnetic field. Up to now most of the measurements use double probe techniques (FAHLESON et al., 1970; MOZER et al., 1979). The difficulties of this measurement are due to the low values of the electric field which does not permit to neglect the perturbations of the electric potential of the natural plasma due to the presence of a spacecraft, mainly if these perturbations are not symmetric. These dissymetries are due for example to the wake effect, to the non equipotentiality of the spacecrafts and to the photoelectrons clouds surrounding these space crafts at high altitude (MOZER et al., 1979). These difficulties sometimes lead to a skepticism on the results of the electric field measurements and often on the existence of the parallel component to the magnetic field (MOZER, 1980). Another independent technique is therefore necessary to compare both set of results leading to a better confidence on these results.
KeywordsPitch Angle Magnetic Field Line Tric Field Parallel Component Acceleration Region
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