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Method to Derive Ion Properties From Juno JADE Including Abundance Estimates for O + and S 2+
Author(s) -
Kim Thomas K.,
Ebert R. W.,
Valek P. W.,
Allegrini F.,
McComas D. J.,
Bagenal F.,
Chae K.,
Livadiotis G.,
Loeffler C. E.,
Pollock C.,
Ranquist D. A.,
Thomsen M. F.,
Wilson R. J.,
Clark G.,
Kollmann P.,
Mauk B. H.,
Bolton S.,
Levin S.,
Nicolaou G.
Publication year - 2020
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2018ja026169
Subject(s) - jovian , ion , jade (particle detector) , physics , jupiter (rocket family) , plasma , magnetosphere , atomic physics , analytical chemistry (journal) , range (aeronautics) , materials science , chemistry , nuclear physics , astrophysics , particle physics , quantum mechanics , space shuttle , astronomy , chromatography , planet , saturn , composite material
The Jovian Auroral Distributions Experiment Ion sensor (JADE‐I) on Juno is a plasma instrument that measures the energy‐per‐charge ( E / Q ) distribution of 0.01 to 46.2 keV/q ions over a mass‐per‐charge ( M / Q ) range of 1– 64 amu/q . However, distinguishing O + and S 2+ from JADE‐I's measurements is a challenging task due to similarities in their M / Q (∼16 amu/q ). Because of this, O + and S 2+ have not been fully resolved in the in situ measurements made by plasma instruments at Jupiter (e.g., Voyager PLS and Galileo PLS) and their relative ratios has been studied using physical chemistry models and ultraviolet remote observations. To resolve this ambiguity, a ray tracing simulation combined with carbon foil effects is developed and used to obtain instrument response functions for H + , O + , O 2+ , O 3+ , Na + , S + , S 2+ , and S 3+ . The simulation results indicate that JADE‐I can resolve the M / Q ambiguity between O + and S 2+ due to a significant difference in their charge state modification process and a presence of a large electric potential difference (∼8 kV ) between its carbon foils and MCPs. A forward model based on instrument response functions and convected kappa distributions is then used to obtain ion properties at the equatorial plasma sheet (∼36 R J ) in the predawn sector of magnetosphere. The number density ratio between O + and S 2+ for the selected plasma sheet crossings ranges from 0.2 to 0.7 (0.37 ± 0.12) and the number density ratio between total oxygen ions to total sulfur ions ranges from 0.2 to 0.6 (0.41 ± 0.09).