Parallel Current Effects on Auroral E-Region Plasma Instabilities.
NAVAL RESEARCH LAB WASHINGTON DC
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Consider the effect of a field aligned current on the development of plasma instabilities in the auroral electrojet. It is found that the inclusion of the parallel current modifies the threshold criteria for the onset of the Farley Buneman instability, and may cause excitation of oblique ion sound waves. Apply these results to the auroral E region and show that they explain some observations of auroral irregularities, for example, the presence of type I irregularities for sub-threshold conditions when the electron Hall drift is less than the ion-sound speed, and the observation of irregularities which are not highly field aligned.
- Atmospheric Physics