Reexamining X-mode suppression and fine structure in artificial E region field-aligned plasma density irregularities
Article first published online: 5 SEP 2013
©2013. American Geophysical Union. All Rights Reserved.
Volume 48, Issue 5, pages 482–490, September-October 2013
How to Cite
2013), Reexamining X-mode suppression and fine structure in artificial E-region field-aligned plasma density irregularities, Radio Sci., 48, 482–490, doi:10.1002/rds.20054., , , , and (
- Issue published online: 15 NOV 2013
- Article first published online: 5 SEP 2013
- Accepted manuscript online: 8 AUG 2013 09:31AM EST
- Manuscript Accepted: 25 JUL 2013
- Manuscript Revised: 18 JUL 2013
- Manuscript Received: 18 APR 2013
- Active experiments;
- Plasma waves and instabilities;
- Ionospheric irregularities;
 Artificial field-aligned plasma density irregularities (FAIs) were generated in the E region of the ionosphere above the High Frequency Active Auroral Research Program facility during campaigns in May and August of 2012 and observed using a 30 MHz coherent scatter radar imager in Homer, Alaska. The purpose of this ionospheric modification experiment was to measure the threshold pump power required to excite thermal parametric instabilities by O-mode heating and to investigate the suppression of the FAIs by simultaneous X-mode heating. We find that the threshold pump power for irregularity excitation was consistent with theoretical predictions and increased by approximately a factor of 2 when X-mode heating was present. A modified version of the Another Model of the Ionosphere (SAMI2) ionospheric model was used to simulate the threshold experiments and suggested that the increase was entirely due to enhanced D region absorption associated with X-mode heating. Additionally, a remarkable degree of fine structure possibly caused by natural gradient drift instability in the heater-modified volume was observed in experiments performed during geomagnetically active conditions.