An assessment of how a combination of shears, field-aligned currents and collisions affect F-region ionospheric instabilities

摘要

We present all in depth study of the fluid limit of a kinetically derived collisional current-driven instability that includes shears in the field-aligned currents as well as collisions. We show how the theory presented here generalizes other theories, including the collisionless current-driven electrostatic ion acoustic instability and its sheared collisionless version. We offer a low-frequencv generalization of the zero frequency ion shear driven instability by minimizing the relative drift magnitude as well as the shears themselves. We discuss the implication of our framework both for strongly field-aligned modes and modes where the wavevectors have arbitrary angles with respect to the ambient magnetic field. We discuss the results in terms of F-region irregularity observations of coherent echoes by ionospheric radars.