Fine-scale cavitation of ionospheric plasma caused by inertial Alfvén wave ponderomotive force

Abstract

Deep, very narrow magnetic-field-aligned density depletions were observed by the Freja spacecraft during auroral oval crossings. These cavities have perpendicular width of the order of the electron skin depth c/ωpe and are associated with low-frequency electromagnetic perturbations and with discrete auroral structures. We demonstrate here that these cavities are likely produced by the ponderomotive force of inertial Alfvén waves.

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