RF-Induced Airglow Observed Using Composite Multispectral Imaging

Atmospheric airglow emissions accompanying artificial ionospheric plasmas occur when the bottom-side ionospheric F-region is exposed to high-power HF heating. These artificial emissions are spectrally similar to those which occur naturally as airglow and aurora, yet they have spatiotemporal behavior commensurate with the heater beam geometry. Interesting dynamics of both the artificial plasma layers and optical emissions have been observed, namely, the presence of multiple descending plasma layers distributed in altitude, mesoscale (10-100 km) bullseye-type airglow emission patterns, and, finally, small-scale (≲ 10 km) field-aligned filaments. We present visualizations of such features exhibited by the heated region using composite multispectral imaging.