Titan's Atomic and Molecular Nitrogen Tori

Abstract

Shematovich et al. (2003) recently showed plasma induced sputtering in Titan's atmosphere is a source of neutral nitrogen in Saturn's magnetosphere comparable to the photo-dissociation source. These sources form a toroidal nitrogen cloud roughly centered at Titan's orbital radius but gravitationally bound to Saturn. Once ionized, these particles contribute to Saturn's plasma. When Titan is inside Saturn's magnetopause, newly formed ions can diffuse inward becoming inner magnetospheric energetic nitrogen where they can sputter and be implanted into icy satellite surfaces. Our 3-D simulation produces the first consistent Titan generated N and N2 neutral clouds; solar UV radiation and magnetospheric plasma subject these particles to dissociation and ionization. The cloud morphologies and associated nitrogen plasma source rates are predicted in anticipation of Cassini data. Since the amount of molecular nitrogen ejected from Titan by photo-dissociation is small, molecular nitrogen ions detection by Cassini will be an indicator of atmospheric sputtering.