  In this work, we model the radial density profile of the outer A ring of
Saturn observed with Cassini cameras (Tiscareno & Harris 2018): An axisymmetric
diffusion model has been developed, accounting for the outward viscous flow of
the ring material, and the counteracting inward drift caused by resonances of
the planet's large outer moons. It has been generally accepted that the 7:6
resonance of Janus alone confines the outer A ring which, however, was
disproved by Tajeddine et al. (2017). We show that the step-like density
profile of the outer A ring is predominantly defined by the discrete
first-order resonances of Janus, the 5:3 second-order resonance of Mimas, and
the overlapping resonances of Prometheus and Pandora.
