Energy balance in the core of the Saturn plasma sheet

This dissertation presents a gas phase water chemistry model of the inner Saturn magnetosphere. Detailed calculations of the plasma sheet electron energy balance establish, for the first time, a direct relation between the forcing energy deposition into the plasma sheet and the state of the ambient plasma sheet electrons. ❧ The two-part model comprises a chemistry code and an energy balance calculation. The chemistry code, coreqg.f90, iteratively solves chemistry rate equations for the thirteen ion and neutral species (H₂O, H₂O⁺, H, H⁺, O, O+, H₂, H₂⁺, O₂, O₂⁺, OH, OH⁺, and H3O+) included in the system. The water chemistry architecture file used by coreqg.f90 completely describes each reaction by specifying the reactant and product species and supplying the collision strength data used to calculate rate coefficients for the chemistry. The input parameter space for the code consists of the number densities and temperatures for the plasma sheet electrons, the heterogeneous electrons, and the selected source species, H₂O and H. ❧ The energy balance calculation operates on the chemistry code outputs and determines the net energy rate for the plasma sheet electrons. Curves for the net plasma sheet electron energy rate vs. input plasma sheet electron temperature, as a function of heterogeneous electron density, are presented. Energy equilibrated plasma sheet electron temperature and gas species partitioning are determined at net zero plasma sheet electron energy rate. ❧ The role played by the Saturn atmospheric heterogeneous hydrogen in maintaining the observed neutral-dominated magnetospheric gas is investigated. The water source rate and energy deposition rate required to maintain the gas at the location of Enceladus (4 Saturn radii (Rs) from Saturn center) are evaluated. Energy relaxation lifetimes for neutral and ion gas species are also determined. Comparison of the model against observation shows basic agreement for the core of the plasma sheet. ❧ The chemistry code input and output files used in the data analysis and plots in this dissertation (plasma sheet electron densities = 50.0, 75.0, and 100.0 cm⁻³) are archived as supplementary files.