Effect of limiting polarization in the Jovian inner magnetosphere

Jovian decameter emission is known to exhibit almost total polarization. We consider the elliptical polarization to be a consequence of linear-mode coupling in the Jovian magnetosphere outside the source region. We determine conditions of emission propagation along the ray path that are necessary for self-consistent explanatation of the polarization observations and show that the ellipticity (axial ratio of the polarization ellipse) is determined by the magnetospheric plasma density ne in a small region a distance of about half the Jovian radius from the radiation source. The plasma density in the region is quite low, ne