This award supports analysis of a unique data set taken at Arecibo Observatory during the period 4-9 June,1989. These data are the first known use of the Imaging Doppler Interferometer (IDI) technique taken in the region of 225 km to 450 km, as well as the first known use of the IDI technique as a diagnostic for an HF heating experiment. It is anticipated that this analysis program will provide additional insight into the cause of HF- induced spread-F. This program will also provide insight into the value of an IDI-based technique as an F-region diagnostic and its appropriateness as an addition to existing and planned HF heating facilities. Although the IDI technique has demonstrated promising results in the mesosphere, its potential in the ionosphere is yet to be determined.
