Modulated High Frequency (HF, 3-30 MHz) heating of the auroral electrojet to generate electromagnetic waves in the Extremely Low Frequency (ELF, 3-3000 Hz) and Very Low Frequency (VLF, 3-30 kHz) bands is investigated in the context of magnetospheric wave injection experiments. The ionospheric heating facility of the High Frequency Active Auroral Research Program (HAARP) is used to excite non-linear amplification of whistler mode waves in the Earth's magnetosphere. Experimental evidence is presented of the first HF heater generated signals experiencing 'ducted' inter-hemispheric propagation and wave-particle interactions resulting in amplification and triggering of free running emissions. The roles of transmitter parameters as well as natural background conditions of the observations are characterized. Dispersion of observed signals is used to determine the magnetospheric propagation paths and associated cold plasma densities. It is found that HAARP induced triggered emissions occur primarily inside the plasmapause and the availability and coupling into magnetospheric 'ducts' is likely one of the limiting factors for observations. Phase and amplitude changes in the observed signals are used to resolve the temporal behavior of the nonlinear resonant current vector that drives amplification. The observed resonant current behavior is discussed in the context of numerical models and used to make inferences about the magnetospheric hot plasma distribution. Ground based capabilities of detection of energetic particle precipitation from the Earth's radiation belts induced by HAARP generated ELF/VLF waves are assessed experimentally and theoretically. A phenomenon of cross-modulation between whistler-mode signals and HF ionospheric heating is observed and investigated as a new method to generate ELF/VLF radiation using an HF ionospheric heater.
|Advisor:||Inan, Umran S.|
|School Location:||United States -- California|
|Source:||DAI-B 70/01, Dissertation Abstracts International|
|Subjects:||Electromagnetics, Atmospheric sciences, Plasma physics|
|Keywords:||Auroral electrojet, High frequency heating, Magnetospheric waves, VLF emissions, Wave injection|
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