Undergraduate Honors Theses

Thesis Defended

Spring 2018

Document Type


Type of Thesis

Departmental Honors



First Advisor

Fran Bagenal

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Jupiter’s moon Io volcanically outgasses roughly 1000kg/s of neutral atoms that, through various ionization mechanisms, end up as plasma in Jupiter’s magnetosphere. This plasma then becomes distributed along magnetic field lines and assumes an overall toroidal structure. We use a diffusive equilibrium model to quantify the structure of the Io plasma torus (IPT). The different sections of the IPT include the cold inner torus (disk), a portion between the disk and the orbit of Io (duct or sometimes called the ribbon), and the remaining warmer outer torus (donut). The disk exists from approximately 4-5.6 RJ, the duct exists from 5.6-6 RJ, and the donut portion extends from 6-10 RJ, where RJ is the radius of Jupiter (1 RJ = 71,492 km). In addition to generating a model that captures these dimensions, our model also accounts for local time variation, mostly in composition, observed by Cassini. This 4D model includes various parameters that can be adjusted in order to gain further insight into the plasma torus. Such parameters include ion and electron temperatures, densities, and distributions, as well as Jupiter’s magnetic field. Using this model we calculate how fast Alfven waves travel through the IPT. We make predictions about the location of the Io auroral footprint (IFT) which will ultimately be compared with Juno’s observations. Additionally, we calculate and analyze the power generated by Io as it orbits in Jupiter’s magnetic field.