SO2 ionization and dissociation in the Io plasma torus

Abstract

Escape of SO2 from Io may be driven by corotating ion impact and energy deposition by the Io flux tube current. The yield of O I per SO2 is estimated in steady state ionization and dissociation of SO2. An average SO2 injection rate of 1028 s−1 is found to be consistent with O I observations in the hot plasma torus. The average densities of S I and SO2 are estimated, but the expected oxygen to sulfur ion ratios from SO2 ionization and dissociation are uncertain. There is substantial loss of neutrals from charge exchange and electron impact on molecular and negative ions (Io plasma torus, mass injection, neutral densities).