Structure and properties of Jupiter’s magnetoplasmadisc

Voyager 1 plasma wave observations have revealed the existence of an Earth‐like continuum radiation trapped in Jupiter’s magnetospheric cavity at frequencies below the solar wind plasma frequency. This radiation serves as an accurate diagnostic of the local electron number density throughout most of Jupiter’s outer magnetosphere and yields information regarding the gross configuration of the magnetoplasmadisc as well as its kinematical properties. Using magnetic field observationswe are able to construct radial profiles of plasma pressuredensityand temperature from 20‐80 R J in the early morning plasma sheet along with plasma sheet crossings and estimated thicknesses. The study suggests that hot protons (∽ 10 keV) are the dominant constituents of the plasma sheet (⋍ 4.2 R J average thickness) out to 80 R J beyond which centrifugal effects take over and distort the sheet towards the rotational equator.