Abundances and Energetics for Water Group Ions in Saturn's Magnetosphere

We present magnetospheric ion composition results obtained from the Cassini Plasma Spectrometer (CAPS) time-of-flight instrument for orbits over a two year period in which Cassini was almost entirely in the dawn magnetosphere. Water group ions (O+,\ OH+,\ H2O+,\ H3O+; or collectively,\ W+) dominate over H+ in the inner magnetosphere to approximately L = 20. W+ ions are seen sporadically out to L = 36. Within the water group,\ O+ dominates at all distances, H3O+ is second to O+ for L < 5, H2O+ is second from L = 5 to L = 8, and OH+ is second for L > 10. The density of H3O+ peaks at L = 3 and drops off rapidly, becoming undetectable beyond L = 11 . The W+ group plasma has both a core and a high energy tail; characteristics of each component have a separate dynamical history and vary as a function of radial distance. The ratio of number densities for the tail to the core is seen to have a broad peak between 10 < L < 20,\ indicating a source mechanism in this location,\ possibly the ring current. Finally,\ we show how the time variation of W+ number densities at specific locations is indicative of bursty events in the magnetosphere.