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Modeling physical chemistry of the Io plasma torus in two dimensions
Author(s) -
Copper M.,
Delamere P. A.,
OvercastHowe K.
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja022767
Subject(s) - torus , magnetosphere , plasma , electron , population , physics , jupiter (rocket family) , electron temperature , astronomy , geometry , space exploration , quantum mechanics , mathematics , demography , sociology
Periodicities in the Io plasma illustrate the rich complexity of magnetosphere‐ionosphere coupling in space plasmas. The confounding System IV period (slower than the rotation of Jupiter's magnetic field ≡ System III) remains a mystery of the torus. Common to both System III and IV are modulations of the superthermal electron population. The small fraction (<1%) of hot electrons plays a vital role in torus physical and chemical properties, modulating the abundance and temperature of ion species. Building on previous models of torus physical chemistry, we have developed a two‐dimensional model that includes azimuthal and radial transport (diffusion equation) while averaging chemical processes in latitude. This paper presents initial results of the model, demonstrating the role of hot electrons in forming a single‐peaked torus structure. The effect of azimuthal shear is investigated as plasma is transported radially outward, showing how the torus properties evolve during transport from a chemically dominated regime (inner torus) to a transport dominated regime (outer torus). Surprisingly, we find that hot electron populations influence torus properties at all radial distances. While many of our results are preliminary, suggestions for future modeling experiments are suggested to provide additional insight into the origin of the ubiquitous superthermal electrons.