First incoherent scatter radar observations of ionospheric heating on the second electron gyro-harmonic

Abstract: 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 2.85MHz, which corresponds to the second electron gyro-harmonic at ~245km 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. [Copyright &y& Elsevier]