The plasma experiment on board meteosat-F2

An electron spectrometer has been designed to aid in the study of spacecraft charging on METEOSAT-F2. Differential energy analysis is performed by a pair of electrostatic analyzers (ESA) in which a time-sequenced variable electrostatic field deflects electrons of selected energies toward an exit aperture where they are counted by Channeltron Electron Multipliers (CEM). The small ESA covers energies ranging from 50 eV to 1 keV to 20 keV. The dwell time at each energy level is 98 ms, with both analyzers operating simultaneously. A complete 16 point spectrum is produced once per second and the 16 data words are transferred to the satellite on command.