When the ionosphere is uniform it reflects radio waves efficiently and makes possible long distance radio communication. It also transmits microwaves between ground and spacecraft with little perturbation. However, the ionospheric plasma is often turbulent with irregularities of many scale sizes, and as such it reflects radio waves poorly and causes scintillation of the ground to spacecraft microwave links. Near the equator the irregularities begin as 100km scale size bubbles of low density plasma rising through the high density plasma, in an instability mechanism equivalent to that of thunderstorm cell formation. The triggering mechanism for this and other more sinusoidal wave type irregularities have not been determined. This grant is for research on the nature of the irregularities and the triggering mechanisms. These are important plasma physics problems and have relevance to the prediction of the quality of communication links.
