Analysis of the Electron Measurements from the PLASMAG-1 Experiment on Board VEGA-2 in the Vicinity of Comet p/ Halley

Measurements of electron spectra, as obtained by the Plasmag- 1 experiment on board Vega 2 in the vicinity of comet Halley, are presented. It is shown that the temperature for thermal electrons gradually decreases when the comet is approached from about 4 × l0⁵ K behind the cometary bow shock to about 2 × l0⁵ K at the cometopause. In the region inside the cometopause a fast increase in the flux of energetic electrons of about 1 keV energy is observed. Various possibilities are discussed regarding the differences in the electron spectra measured by Vega 2 and Giotto, respectively.