Leonardo Regoli

Survey of pickup ion signatures in the vicinity of Titan using CAPS/IMS†

Pickup ion detection at Titan is challenging because ion cyclotron waves are rarely detected in the vicinity of the moon. In this work, signatures left by freshly produced pick up heavy ions (m/q ∼ 16 to m/q ∼ 28) as detected in the plasma data by the CAPS/IMS instrument on-board Cassini are analyzed. In order to discern whether these correspond to ions of exospheric origin, one of the flybys during which the reported signatures were observed is investigated in detail. For this purpose, ion composition data from time of flight measurements and test particle simulations to constrain the ions origin are used. After being validated, the detection method is applied to all the flybys for which the CAPS/IMS instrument gathered valid data, constraining the region around the moon where the signatures are observed. The results reveal an escape region located in the anti-Saturn direction as expected from the nominal corotation electric field direction. These findings provide new constraints for the area of freshly produced pickup ion escape, giving an approximate escape rate of 3.3−2+3×1023ions·s−1.