Voyager encounters with Jupiter's magnetosphere: results of the low energy charged particle (LECP) experiment

The two Voyager spacecraft encountered the planet Jupiter and its magnetosphere during March and July 1979. Included in the payload was an instrument designed to measure hot plasmas and high energy charged particles (Esub(ion) >approximately 30 keV, Esub(e) >approximately 15 keV). These measurements have revealed that the Jovian magnetosphere is filled with a hot (20-40 keV) multicomponent plasma consisting primarily of hydrogen, helium, oxygen, and sulfur ions which is moving in the corotation direction out to the magnetopause on the dayside (50-80 Rsub(J)) and to a distance of 100-150 Rsub(J) on the nightside. Beyond approximately 150 Rsub(J) the plasma flow changes abruptly to a generally anti-solar direction and continues in that direction to >approximately 360 Rsub(J) at the 3 AM meridian. Hot plasma velocities in this region range from approximately 300 to >approximately 1000 km/sec, and the composition is similar to that in the inner part of the magnetosphere. This phenomenon has the characteristics of a wind and has been named magnetospheric wind. An overall phenomenological model incorporating these features is presented and discussed. (Auth.)