Survey of Voyager plasma science ions at Jupiter: 3. Protons and minor ions

Bodisch, K. M.; Dougherty, L. P.; Bagenal, F.

doi:10.1002/2017ja024148

Cited by 33 publications

(54 citation statements)

References 86 publications

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“…The number density estimates of jovian magnetospheric ions using Voyager Plasma Science (PLS) (Bridge et al, ) have been presented in several studies (Bagenal & Sullivan, ; Bagenal et al, ; Bodisch et al, ; Dougherty et al, ; McNutt et al, ). They selected intervals where the peaks in the count‐ E / Q distributions were clearly resolvable (i.e., cold plasma).…”

Section: Discussionmentioning

confidence: 99%

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Method to Derive Ion Properties From Juno JADE Including Abundance Estimates for O⁺ and S²⁺

et al. 2020

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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 S2+ from JADE‐I's measurements is a challenging task due to similarities in their M/Q (∼16 amu/q). Because of this, O+ and S2+ 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+, O2+, O3+, Na+, S+, S2+, and S3+. The simulation results indicate that JADE‐I can resolve the M/Q ambiguity between O+ and S2+ 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 RJ) in the predawn sector of magnetosphere. The number density ratio between O+ and S2+ 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).

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Section: Discussionmentioning

confidence: 99%

“…However, the physical chemistry model only can cover radial distances up to ∼10 R J and the 1.02 value is obtained assuming freezing‐in of the charge state. This assumption is used in previous studies (e.g., Bagenal et al, , ; Bodisch et al, ; Dougherty et al, ) to obtain ion properties from Voyager PLS and Galileo PLS.…”

Section: Discussionmentioning

confidence: 99%

Method to Derive Ion Properties From Juno JADE Including Abundance Estimates for O⁺ and S²⁺

et al. 2020

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“…In other planetary systems, the scaling should apply for other heavy unmagnetized species, such as SO 2 (Bodisch et al, 2017). In Earth's geospace, O + is the most likely candidate.…”

Section: Discussion and Summarymentioning

confidence: 99%

The Impact of Oxygen on the Reconnection Rate

Tenfjord

Hesse

Norgren

et al. 2019

Geophysical Research Letters

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We investigate the role of a background oxygen population in magnetic reconnection, using particle‐in‐cell simulations. We run several simulations, with different initial oxygen temperatures and densities, to understand how the reconnection rate is influenced, as oxygen is captured by the reconnection process. The oxygen remains approximately demagnetized on the relevant time and spatial scales and therefore has little direct (i.e., immediate mass loading) effect on the reconnection process itself. The reconnection rate is independent of the initial oxygen temperature but clearly dependent on the density. The reduced reconnection rate is twice as fast as predicted by mass loading. We describe a mechanism where the oxygen population (and the associated electrons) acts as an energy sink on the system, altering the energy partitioning. Based on a scaling analysis, we derive an estimate of the reconnection electric field that scales as (1+no/np)−1, where no and np is the oxygen and proton densities, respectively.

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“…The measured abundances of protons (H + ) and other minor ions (Na + and SO 2 + ) are discussed in Bodisch et al . [, hereafter called Paper 3].…”

Section: Introductionmentioning

confidence: 99%

Survey of Voyager plasma science ions at Jupiter: 2. Heavy ions

2017

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We take the plasma parameters derived by Bagenal et al. (2017) from Voyager plasma science data in the Jovian magnetosphere and examine the radial profiles of density, temperature, composition, and azimuthal flow. The plasma sheet shows a relatively uniform structure of decreasing electron density (Ne) and increasing temperature out to about 20 RJ, but beyond about 15 RJ there is increasing disorder with sporadic blobs of cold plasma. These small (~0.5 RJ) blobs of cold (~20 eV) plasma make a minor contribution to the net outward flux of iogenic plasma. The ion composition in the cold blobs is consistent with the ion abundances derived from physical chemistry models extending from 6 to ~9 RJ, whereupon the collisional reactions slow down and radial transport speeds up, effectively freezing in the ion composition to the following abundances: O+/Ne = 15–22%, S++/Ne = 10–19%, O++/Ne = 4–8%, S+++/Ne = 4–6%, and S+/Ne = 1–5%. Beyond about 7 RJ the component of hot (suprathermal, approximately hundreds of eV) ions becomes a significant fraction of the total density. The radial profile of the plasma's azimuthal flow speed shows that corotation begins to breakdown at about 9 RJ, dipping down to about 20% below corotation before increasing back up to corotation briefly (~17–20 RJ), reaching an asymptotic value of about 225 km/s (corresponding to rigid corotation at ~18 RJ). We present a 2‐D model of the plasma sheet beyond 6 RJ based on simple functions for the equatorial profiles of plasma properties and steady state diffusive equilibrium along magnetic flux tubes. Cold plasma blobs in the Jovian plasma sheet show ion composition consistent with physical chemistry models. Azimuthal flow speeds dip below corotation 9–15 Jovian radii. Radial profiles of plasma properties are combined to make a 2‐D model of plasma sheet.

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Survey of Voyager plasma science ions at Jupiter: 3. Protons and minor ions

Cited by 33 publications

References 86 publications

Method to Derive Ion Properties From Juno JADE Including Abundance Estimates for O⁺ and S²⁺

Method to Derive Ion Properties From Juno JADE Including Abundance Estimates for O⁺ and S²⁺

The Impact of Oxygen on the Reconnection Rate

Survey of Voyager plasma science ions at Jupiter: 2. Heavy ions

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Survey of Voyager plasma science ions at Jupiter: 3. Protons and minor ions

Cited by 33 publications

References 86 publications

Method to Derive Ion Properties From Juno JADE Including Abundance Estimates for O+ and S2+

Method to Derive Ion Properties From Juno JADE Including Abundance Estimates for O+ and S2+

The Impact of Oxygen on the Reconnection Rate

Survey of Voyager plasma science ions at Jupiter: 2. Heavy ions

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Method to Derive Ion Properties From Juno JADE Including Abundance Estimates for O⁺ and S²⁺

Method to Derive Ion Properties From Juno JADE Including Abundance Estimates for O⁺ and S²⁺