The investigators will develop a high frame-rate tomographic imaging facility, and a physics-based inversion methodology, in order to quantify three-dimensional motions of the aurora at its finest scales. Although several theories have been suggested to account for structuring at these scales, determining which model is correct and under which circumstance requires knowledge of two parameters not directly observed by a single imaging system: 1) the transverse motion or spreading) of auroral forms with respect to the convecting frame of reference, and 2) the change in average energy of the primary particle spectrum, manifested in the apparent vertical deformation of auroral forms. The former addresses the dispersion of energy across magnetic lines of force, while the latter addresses changes in coupling between electromagnetic and kinetic energy. The new approach uses a physical model of particle penetration in order to regularize the poorly observed field-aligned dimension. In addition to regularizing the problem, this approach provides access to the physical quantity of interest: the space-time variability in the primary electron spectrum. The research leverages technologies recently developed in the commercial and defense sectors (e.g., Electron Multiplying CCD cameras, solid state drives, millisecond GPS synchronization). If successful, the research will provide new observational evidence needed to address a fundamental unresolved question space physics. The results will contribute to the understanding of universal plasma processes occurring throughout the cosmos. The project supports an early career space scientist, a graduate student in engineering, and several undergraduate research assistants.
