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www.ann-geophys.net/23/1585/2005/
doi:10.5194/angeo-23-1585-2005
© European Geosciences Union 2005
Artificial optical emissions at HAARP for pump frequencies near the third and second electron gyro-harmonic
1Space Vehicles Directorate, Air Force Research Laboratory, Hanscom AFB, Massachusetts, USA
2Communication Systems, Lancaster University, Lancaster, UK
3Honorary Research Fellow, University of Kwazulu-Natal, Durban, South Africa
4Geophysical Institute, University of Alaska, Fairbanks, USA
5STARLab, Stanford University, Stanford CA, USA
6Dept. Electrical & Computer Engineering, Cornell University, Ithaca NY, USA
7Advanced Power Technologies, Washington D.C., USA
8Geospace Research, El Segundo CA, USA
Abstract. High-power high-frequency radio waves beamed into the ionosphere cause plasma turbulence, which can accelerate electrons. These electrons collide with the F-layer neutral oxygen causing artificial optical emissions identical to natural aurora. Pumping at electron gyro-harmonic frequencies has special significance as many phenomena change their character. In particular, artificial optical emissions become strongly reduced for the third and higher gyro-harmonics. The High frequency Active Auroral Research Program (HAARP) facility is unique in that it can select a frequency near the second gyro-harmonic. On 25 February 2004, HAARP was operated near the third and passed through the second gyro-harmonic for the first time in a weakening ionosphere. Two novel observations are: firstly, a strong enhancement of the artificial optical emission intensity near the second gyro-harmonic, which is opposite to higher gyro-harmonics; secondly, the optical enhancement maximum occurs for frequencies just above the second gyro-harmonic. We provide the first experimental evidence for these effects, which have been predicted theoretically. In addition, irregular optical structures were created when the pump frequency was above the ionospheric critical frequency.
Keywords. Active experiments – Auroral ionosphere – Wave-particle interactions
Full Article (PDF, 341 KB) Special Issue
Citation: Kosch, M. J., Pedersen, T., Hughes, J., Marshall, R., Gerken, E., Senior, A., Sentman, D., McCarrick, M., and Djuth, F. T.: Artificial optical emissions at HAARP for pump frequencies near the third and second electron gyro-harmonic, Ann. Geophys., 23, 1585-1592, doi:10.5194/angeo-23-1585-2005, 2005. Bibtex EndNote Reference Manager XML
