Hot plasma environment at Jupiter - Voyager 2 results

Preliminary results are reported from measurements made with the low-energy charged particle (LECP) instrument on Voyager 2 as it approached and traversed the Jovian magnetosphere. The primary objectives of the LECP instrument were to make measurements of the hot plasma (no less than about 20 keV and no less than about 28 keV for electrons and ions, respectively), to characterize the composition of the hot plasma and energetic-particle population, and to determine the particle flows and spatial distributions. In addition, the effects associated with the possible wake of Ganymede are discussed. Attention is given to inbound and outbound passes, along with Jovian plasma characteristics. The results suggest that the Jovian magnetosphere is confined by a plasma boundary rather than a conventional magnetopause. Inside the plasma boundary there exists a discontinuity at about 50-60 Jupiter radii, and the region inside this discontinuity is termed the 'inner plasmasphere'.