Physics
Scientific paper
Dec 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008agufmsa42a..08c&link_type=abstract
American Geophysical Union, Fall Meeting 2008, abstract #SA42A-08
Physics
2403 Active Experiments, 6929 Ionospheric Physics (1240, 2400), 7803 Active Perturbation Experiments
Scientific paper
ELF/VLF (300 Hz - 30 kHz) waves are difficult to generate with conventional antennae due to their extraordinary long wavelengths, and the good conductance of the Earth at these frequencies. Recently, ELF and VLF waves have been generated using HF (3-10 MHz) heating of the lower ionosphere, in the presence of natural currents such as the auroral electrojet, which modulates the ionospheric conductivity and therefore turns the lower ionosphere into a large radiating element. The recently upgraded HAARP facility, near Gakona Alaska, utilizes 3.6 MW of HF power, along with an unprecedented ability to steer the HF heating beam over a large area extremely rapidly. Since the completion of the upgrade in 2007, the first successful implementation of techniques such as geometric modulation [Cohen et al. 2008, Borisov et al. 1998], and beam painting [Papadopoulos et al. 1989] have occurred. These results have shown as much as 7-11 dB improvement in the signal strengths, as well as the first ability to direct ELF/VLF signals via an unprecedented ELF/VLF phased array. Here, we use a combination of experimental and theoretical investigations to discuss the optimization of ELF/VLF generation via HF heating, including the effect of HF and ELF frequency on the amplitude and the directional pattern for various generation techniques. The experimental observations occur over an array of receivers across Alaska. The theoretical formulation utilizes a 3D model of the HF heating and subsequent electron cooling processes, leading to spatial structure of modulated ionospheric conductivities, the results of which are input into a model of ELF/VLF propagation in the Earth-ionosphere waveguide.
Cohen Morris B.
Golkowski M. A.
Inan Umran S.
Lehtinen Nikolai G.
No associations
LandOfFree
Optimizing ELF/VLF generation via HF heating utilizing beam motion does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Optimizing ELF/VLF generation via HF heating utilizing beam motion, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optimizing ELF/VLF generation via HF heating utilizing beam motion will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1245459