Survey of Ion Properties in Jupiter's Plasma Sheet: Juno JADE‐I Observations
Thomas K. Kim, R. W. Ebert, P. W. Valek, F. Allegrini, D. J. McComas, F. Bagenal, J. E. P. Connerney, G. Livadiotis, M. F. Thomsen, R. J. Wilson, S. J. Bolton
Abstract
Abstract This study presents a survey of ion flow speed, density, temperature, and composition observed by the Jovian Auroral Distributions Experiment Ion (JADE‐I) sensor on Juno from 10–40 R J in the dawn to midnight sector of Jupiter's magnetosphere. The survey covers Juno orbits 5–22, and the observations are separated by equatorial (|z mag [R J ]| ≤ 1.5) and off‐equator (|z mag [R J ]|>1.5) regions. Plasma parameters for H + , O + , O 2+ , O 3+ , Na + , S + , S 2+ , and S 3+ are derived by forward modeling JADE‐I's energy‐per‐charge versus time‐of‐flight spectra using omni‐directional averaged convected kappa distributions and modeled instrument responses. O + and S 2+ are resolved via a ray‐tracing simulation based on carbon‐foil effects. The ion flow speed increases with radial distance and is comparable to rigid corotation speed out to ∼20 R J . Ion number densities decrease with radial distance, the primary species being H + , O + , and S 2+ . The relative contribution of H + and S 2+ increases and decreases, respectively, in the off‐equator regions, supporting the interpretation that the latitudinal distribution of ions is mass dependent. The O + to S 2+ and ΣO n+ to ΣS n+ number density ratios are variable, the 5 R J bin averages for O + to S 2+ ranging from ∼0.75–1.5 (equator) and ∼1.1–1.8 (off‐equator) and ΣO n+ to ΣS n+ from ∼0.6–0.9 (equator) and ∼0.8–1.1 (off‐equator). Both proton and heavy ion temperatures show order of magnitude increases between 10 and 20 R J and range from ∼100 eV to 10 keV and 1 keV to a few tens of keV , respectively.