Electrodynamical structuring and heating of the ionosphere revealed through low-enery ion imaging

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Of the numerous questions that arise in the study of space, two recur time and again: Why is the universe so highly structured? And, how do plasmas in space become so energetic? The fine structure of coronal loops and the million-Kelvin plasmas that populate them are prime examples. While less widely appreciated, the auroral ionosphere is no exception. In a system whose boundaries are measured in Earth radii, the dominant spatial scales of auroral forms range from tens of kilometers to tens of meters. And, auroral plasmas at altitudes as low as 500 km have been observed to reach temperatures rivaling those of the solar corona. In the aurora, both the high degree of structure and the surprisingly high energies owe their existence to electromagnetic forces, or more specifically to the interaction of the solar wind, the magnetosphere and the ionosphere through mega-Ampere-scale electric currents and the magnetic fields that thread them.