Discrepancy in proton flux extrapolation along field lines in the middle Jovian magnetosphere

An attempt is made to explain the observed modulation of the electron and proton fluxes between 20 and 30 Jupiter radii on the basis of adiabatic theory and assumed symmetry with Jovigraphic longitude. Liouville's theorem is applied with the assumption that particles move conserving their magnetic moments. A magnetic model which matches the intensity and direction of the magnetic field along the Pioneer 10 trajectory is used for determining the positions of the equatorial crossings. Energetic electrons (1.3 MeV) compared in this way appear to be consistently described. Protons, on the other hand, show much weaker fluxes at the off-equatorial points than would be expected by this simple application of Liouville's theorem. Reasons for this discrepancy are offered.