Search

The magnetospheres of giant planets are governed by the interplay of these planets’ fast rotation, the solar wind and inner plasma sources. In the Saturn and Jupiter magnetospheres, plasma is mainly produced by the ionization of neutral gas tori at the radial location of active moons: Io at Jupiter and Enceladus at Saturn. The mechanisms by which these moon-associated plasma sources are re- distributed throughout these magnetospheres involve both plasma motions and magnetic flux tube exchanges. These motions are coupled to the rotation of the planets through electric current systems originating in the equatorial plasma disk and closing into their upper atmosphere and ionosphere. Models of the net effects of these different mechanisms on the radial transport of plasma are needed to adequately reproduce the observed populations of electrons and ions in the magnetospheres of giant planets and to establish the net budgets of exchange of plasma, angular momentum and energy between moons, magnetospheres and their host planets. Up to now, two different types of transport models have been developed. The first type (Cowley and Bunce, 2001; Cowley et al., 2005 and following studies) assumes an infinitely thin plasma disk with null temperature and pressure and derives the transport of angular momentum in the magnetosphere with due account of magnetosphere-ionosphere- thermosphere (MIT) coupling. In the second type of model (Bagenal and Delamere, 2011; Ng et al., 2018), radial diffusion of full flux tubes with finite temperature is calculated throughout the disk, taking into account hydrodynamical properties of the plasma and turbulent heating in the absence of MIT coupling. A self-consistent modelling of radial transport in the magnetosphere of giant planets requires the unification of the two approaches into a full description of the interactions between the plasma disk content, the magnetosphere and the ionosphere-thermosphere of the planet. In this communication, we introduce an approach combining these two types of models to design a more general model. This new type of model will describe radial transport of plasma, angular momentum and energy in the Jupiter and Saturn magnetospheres taking into account both diffusive/advective plasma transport and exchange of angular momentum with the planet’s upper atmosphere. It will be tested against magnetosphere observations by the Juno mission at Jupiter and the Cassini mission at Saturn., {"references":["Ng, C. S. et al. (2018) : \"Radial Transport and Plasma Heating in Jupiter's Magnetodisc\", Journal of Geophysical Research : Space Physics, doi : 10.1029/2018JA025345","Bagenal et Delamere (2011) : \"Flow of Mass and Energy in the Magnetospheres of Jupiter and Saturn\", Journal of Geophysical Research : Space Physics, 116(A05209), doi : 10.1029/2010JA016294","Cowley, S. W. H., and E. J. Bunce (2001) : \"Origin of the main auroral oval in Jupiter's cou- pled magnetosphere-ionosphere system\", Planetary and Space Science, 49, 1067, doi : 10.1016/S0032- 0633(00)00167-7","Cowley, S. W. H., Alexeev, I. I. et al. (2005) : \"A simple axisymmetric model of magnetosphere- ionosphere coupling currents in Jupiter's polar ionosphere\", Journal of Geophysical Research : Space Physics, 110(A11), A11209, doi : 10.1029/2005JA011237"]}

Provided here are ASCII dumps of the processed data that appears in the figures of the subject paper. The enclosed files begin with a PDF of the paper that serves to identify, display, and document the figures in question. Below is the paper abstract. Abstract: The low-altitude, polar orbit of the Juno mission allows the Jupiter Energetic Particle Detector Instrument (JEDI) to view into, and resolve, the loss cone of energetic ions comprising the low-altitude extension of Jupiter’s ring current ions. For regions mapping from just inside Ganymede’s orbit, to well beyond Ganymede’s orbit, energetic ions (> 50 keV H+ and >130 keV Oxygen and Sulfur ions) are strongly scattered into the loss cone, and lost to the magnetosphere, at the “strong diffusion limit” at essentially all times. We conclude, by arguing against magnetic curvature scattering, that the cause is waves, perhaps associated with Alfvénic variations previously documented in this equatorial region. Scattering is generally weak or non-existent near the orbits of the moons Europa and Io, except for the regions just downstream of the co-rotating plasmas. For Io, we sometimes observe moderate, but not saturated, scattering within roughly 60° downstream. Significantly, scattering is weak or non-existent just upstream of Io’s position, an asymmetry echoed in some previous wave observations. A preliminary accounting of the total (longitude-averaged) scattering losses near Io’s orbit yields loss rates of order 4% - 5% percent of the strong diffusion limit for H+, and 5%-7% for heavy ions (O+S). We conclude that near Io’s orbit, charge exchange losses likely dominate over scattering losses for heavy ions, and for the lower energy H+ ions (roughly

The radiation belts of the giant planet Jupiter are populated by very energetic electrons, protons and heavy ions. On one hand, these charged particles represent a major threat to exploration missions. On the other hand, understanding the radiation belt particles origin and distributionis a fundamental question of the broad Space Physics research domain. The physical model Salammbô of ONERA addresses the two previous challenges. It has been developed during two successive previous PhD thesis that ended in 2004 [Santos-Costa, 2001; Sicard, 2004]. Previous work has enabled to predict and study the electrons inward of Europa’s orbit (9 Rj) and the protons inward of the volcanic moon Io (6 Rj). Since 2004, the Galileo mission that was in orbit around Jupiter until 2003 has provided many inputs regarding the Jovian radiation belts and the environment that shape them. This PhD thesis revisits the electron model and expands the proton’s one up to Europa’s orbit. Our modeling effort shows that, in particular, electromagnetic waves propagating between the orbits of the moons Io and Europa create strong particle losses within the radiation belts, as the charged particles are precipitated in the Jovian atmosphere. In addition, our models are better suited than what has been proposed by previous work to predict the harsh radiative environment near Jupiter., Les ceintures de radiations de la planète géante Jupiter sont constituées d’électrons, de protons et d’ions lourds de très haute énergie. Ces particules chargées représentent un risque majeur pour les satellites artificiels cherchant à explorer Jupiter. Dans le même temps, comprendrel’origine et la répartition de ces particules est une problématique fondamentale du domaine de la Physique de l’Espace. Le modèle physique Salammbô de l’ONERA répond aux deux enjeux précédents. Il a été développé pour le cas de la planète géante au cours de deux thèses successives qui se sont terminées en 2004 [Santos-Costa, 2001 ; Sicard, 2004]. Les travaux précédents ont permis de mettre en place un modèle d’électrons qui s’étend de l’atmosphère de Jupiter jusqu’à l’orbite d’Europe (9 Rj) et un modèle de protons jusqu’à l’orbite de la lune volcanique Io (6 Rj ). Depuis cette date, la mission américaine Galileo, qui fut en orbite autour de Jupiter jusqu’en 2003, a livré de nombreuses informations sur les ceintures de radiations et sur l’environnement qui influence celles-ci. Cette thèse revisite le modèle d’électrons et étend le modèle de protons jusqu’à l’orbite d’Europe. Cela permet, en particulier, de montrer que les ondes électromagnétiques se propageant entre les orbites des lunes Io et Europe induisent des pertes significatives de particules, celles-ci étant précipitées dans l’atmosphère de Jupiter. Les modèles proposés au cours de cette thèse sont également mieux à même de prédire l’environnement extrême et limitant des ceintures de radiations que les précédents travaux.

The radiation belts of the giant planet Jupiter are populated by very energetic electrons, protons and heavy ions. On one hand, these charged particles represent a major threat to exploration missions. On the other hand, understanding the radiation belt particles origin and distributionis a fundamental question of the broad Space Physics research domain. The physical model Salammbô of ONERA addresses the two previous challenges. It has been developed during two successive previous PhD thesis that ended in 2004 [Santos-Costa, 2001; Sicard, 2004]. Previous work has enabled to predict and study the electrons inward of Europa’s orbit (9 Rj) and the protons inward of the volcanic moon Io (6 Rj). Since 2004, the Galileo mission that was in orbit around Jupiter until 2003 has provided many inputs regarding the Jovian radiation belts and the environment that shape them. This PhD thesis revisits the electron model and expands the proton’s one up to Europa’s orbit. Our modeling effort shows that, in particular, electromagnetic waves propagating between the orbits of the moons Io and Europa create strong particle losses within the radiation belts, as the charged particles are precipitated in the Jovian atmosphere. In addition, our models are better suited than what has been proposed by previous work to predict the harsh radiative environment near Jupiter.; Les ceintures de radiations de la planète géante Jupiter sont constituées d’électrons, de protons et d’ions lourds de très haute énergie. Ces particules chargées représentent un risque majeur pour les satellites artificiels cherchant à explorer Jupiter. Dans le même temps, comprendrel’origine et la répartition de ces particules est une problématique fondamentale du domaine de la Physique de l’Espace. Le modèle physique Salammbô de l’ONERA répond aux deux enjeux précédents. Il a été développé pour le cas de la planète géante au cours de deux thèses successives qui se sont terminées en 2004 [Santos-Costa, 2001 ; Sicard, 2004]. Les travaux précédents ont permis de mettre en place un modèle d’électrons qui s’étend de l’atmosphère de Jupiter jusqu’à l’orbite d’Europe (9 Rj) et un modèle de protons jusqu’à l’orbite de la lune volcanique Io (6 Rj ). Depuis cette date, la mission américaine Galileo, qui fut en orbite autour de Jupiter jusqu’en 2003, a livré de nombreuses informations sur les ceintures de radiations et sur l’environnement qui influence celles-ci. Cette thèse revisite le modèle d’électrons et étend le modèle de protons jusqu’à l’orbite d’Europe. Cela permet, en particulier, de montrer que les ondes électromagnétiques se propageant entre les orbites des lunes Io et Europe induisent des pertes significatives de particules, celles-ci étant précipitées dans l’atmosphère de Jupiter. Les modèles proposés au cours de cette thèse sont également mieux à même de prédire l’environnement extrême et limitant des ceintures de radiations que les précédents travaux.