Browsing Physics by Subject "Auroras"
Now showing items 1-2 of 2
Modeling the generation and propagation of dispersive waves in the giant magnetospheres through mass loading and transport using hybrid simulationThe magnetodiscs of Jupiter and Saturn are characterized by turbulence in the magnetic field. Broadband spectra of precipitating electrons at Jupiter suggest that a process is underway whereby large scale perturbations undergo a turbulent cascade in the magnetodisc. The cascade couples large perturbations to dispersive scales (kinetic and inertial Alfvén waves). Plasma transport in the rapidly rotating giant magnetospheres is thought to involve a centrifugally-driven flux tube interchange instability, similar to the Rayleigh-Taylor (RT) instability. Mass loading from satellites such as Io and Enceladus also cause dispersive wave formation in the magnetosphere, which is a source for broadband aurora. This dissertation presents a set of hybrid (kinetic ion/fluid electron) plasma simulations of the RT instability and the Io flux tube using conditions appropriate for the magnetospheres of Jupiter and Saturn. Both the Io torus and the planetary magnetodisc act as resonant cavities for counter propagating waves, which creates turbulence. The transmission ratio of wave power from the Io torus is 53%, an improvement from previous models (20% transmission), which is important to the generation of the Io auroral footprint. The onset of the RT instability begins at the ion kinetic scale and cascades to larger wavelengths. Strong guide field reconnection is a mechanism for radial transport of plasma in the magnetodisc. Counter propagating waves within the RT instability is the origin of turbulence within the magnetodisc.
Studying auroral microphysics using multiple optically tracked rocket sub-payloadsThere is insufficient knowledge of scale length parameters associated with ionospheric plasma structures. Using a novel technique combining rocket-based instrument data with ground-based optical and instrumental data measurements, ISINGLASS attempts to determine the spatial scale lengths over which parameter differences in auroral arcs present in the upper ionosphere. Determination of such scale lengths has the propensity to strengthen preexisting models of magnetosphere-ionosphere interactions. While analysis is not complete and the extent of such scale lengths is still unknown, after completion of the experiment phase of the mission, differences in measurements have been found that cannot be accounted for through experimental error. This shows the existence of a critical scale length within the distances measured, and the techniques used present a reliable method with which to launch a future campaign.