Investigation of Shear Driven Wave Generation at Dipolarization Fronts

The highly stressed, Earth-ward propagating plasma resulting from a reconnection event is known as a dipolarization front because of its strong dipole (Bz) field. At its Earth-facing edge, there are sharp discontinuities in plasma flow, density, temperature, and electromagnetic fields. This region of space contains large releases of energy driven by sheared flows and fields. Our work is based on a non-local theory for the generation of shear-driven electrostatic Electron-Ion Hybrid waves (EIH) with frequencies near the lower hybrid frequency. We compare analytical and numerical dispersion relations to find their range of agreement. We find that the spatial length scale of the waves diverges at low-velocity shears.  We then compare numerical simulations and experimental data to establish a threshold for wave growth. We expect that the likely length scale of the threshold for wave growth is at the electron Larmore radius.

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