HR: 1330h
AN: SM22B-0251    [PDF]
TI: Particle Simulations of the Io Inner Torus Boundary
AU: * Cowee, M M
EM: mcowee@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA 90095
AU: Wang, Y
EM: ylwang@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA 90095
AU: Russell, C T
EM: ctrussel@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA 90095
AU: Gurnett, D A
EM: dag@space.physics.uiowa.edu
AF: Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242
AB: The Galileo spacecraft passed inside the orbit of Io during the A34 pass in November 2002, detecting a sharp inner boundary to the Io plasma torus. This boundary sits at a jovicentric distance between 4.5 and 5 Rj. A model of torus formation utilizing the neutralization and reionization of mass loaded ions from the Io atmosphere predicts an inner torus boundary which depends on the torus flow velocity in the pickup region. If the ion is picked up in the full corotational regime, the associated fast neutrals can move to within 3.5 Rj. However, if the ion is picked up in a flow regime decelerated by only 15 km/s, the fast neutrals reach only to about 4.7 Rj. Thus small variations in the Io-torus interaction region can move the inner edge of the torus. In the model the density dropoff across the boundary is not steep as was observed by Galileo. It is possible that the outward radial transport of the cold torus ions via flux tubes moves the inner boundary and changes the radial density profile of the torus. We add such transport to our model to investigate this possibility.
DE: 6218 Jovian satellites
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting