Zebra Stripe Patterns in Energetic Ion Spectra at Saturn

Magnetospheric convective electric fields that could radially transport particles adiabatically, may leave their imprints in the form of energy-time dispersed patterns termed "zebra stripes". Inspired by comprehensive studies on zebra stripes in Earth's electron radiation belts, similar electron signatures were found and explained in Saturn's inner magnetosphere. Using Cassini Magnetosphere Imaging Instrument observations, we demonstrate that the zebra-stripes in proton and water group ion spectrograms at the energy range from 30 keV to similar to 1 MeV, which coexist with electron zebra-stripes, can be traced to the same electric field, even though the associated radial flows were originally thought to be too slow to disturb the fast azimuthal energetic ion drift. The simultaneous observations of zebra stripes in electrons and ions further establish the importance of the planet's noon-midnight electric field as a regulator of radiation belt dynamics.