Kosch, M. J., Gustavsson, B., Heinselman, C., Pedersen, T., Rietveld, M. T., Spaleta, J., … & Hughes, J. (2009). First incoherent scatter radar observations of ionospheric heating on the second electron gyro-harmonic. Journal of atmospheric and solar-terrestrial physics, 71(17-18), 1959-1966.
We report first results from a unique experiment performed at the HIPAS ionospheric modification facility in conjunction with the Poker Flat incoherent scatter radar in Alaska. High-power radio waves at 2.85 MHz, which corresponds to the second electron gyro-harmonic at ~245 km altitude, were transmitted into the nighttime ionosphere. Clear evidence of F-region ionospheric electron temperature enhancements were found, for the first time at this pump frequency, maximizing when the pump frequency is close to the second gyro-harmonic and double resonance. This is consistent with previous pump-enhanced artificial optical observations. We estimate the plasma heating efficiency to be approximately double that for higher pump frequencies.