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Carl Siefring
Public Documents
2
HF Induced Modifications of the Electron Density Profile in the Earth's Ionosphere Us...
Alexey Vladimirovich Shindin
and 6 more
June 05, 2021
We discuss results on plasma density profile modifications in the F-region ionosphere caused by HF heating with the frequency f0 in the range [(-150 kHz)-(+75 kHz)] around the 4th electron gyroharmonic 4fc. The experiments were conducted at the HAARP facility on June 2014. The multi-frequency Doppler Sounder (MDS) which measures the phase and amplitude of reflected sounding radio waves complemented by the observations of the Stimulated Electromagnetic Emission (SEE) were used for the diagnostics of the plasma perturbations. We detected noticeable plasma expulsion from the reflection region of the pumping wave, and from the upper hybrid region, the expulsion from the latter one had been strongly suppressed for f0≈4fc. The plasma expulsion from the upper hybrid region was accompanied with the sounding wave’s anomalous absorption slower developing for f0≈4fc. Also, slower developing and weaker expulsion was detected for the height region between the pump wave reflection and upper hybrid altitudes.
Strong Amplification of ELF/VLF Signals in Space Using Neutral Gas Injections from a...
Paul Bernhardt
and 12 more
September 10, 2020
The first demonstration of rocket exhaust driven amplification (REDA) of whistler mode waves occurred on 26 May 2020 by transferring energy from pickup ions in a rocket exhaust plume to EM waves. The source of coherent VLF waves was the Navy NML Transmitter at 25.2 kHz located in LaMoure, North Dakota. The topside ionosphere at 480 km altitude became an amplifying medium with a 60 second firing of the Cygnus BT-4 engine. The rocket engine injected exhaust as a neutral cloud moving perpendicular to field lines that connected the NML transmitter to the VLF Radio Receiver Instrument (RRI) on e-POP/SWARM-E. Charge exchange between the ambient O+ ions and the hypersonic water molecules in the exhaust produced H2O+ ions in a ring-beam velocity distribution. The 25.2 kHz VLF signal from NML was amplified by 30 dB for a period 77 seconds as observed by the RRI. Simultaneously, preexisting coherent ELF waves at 300 Hz were amplified by 50 dB during and after the Cygnus burn. Extremely strong coherent emissions and quasi-periodic bursts in the 300 to 310 Hz frequency range lasted for 200 seconds after the release. The excitation of an ELF whistler cavity may have lasted even longer, but the orbit of the SWARM-E/e-POP moved the RRI sensor away from the wave emission region. The amplified 300 Hz ELF waves may have gained even more energy by cyclotron resonance with radiation belt electrons as they were ducted between geomagnetic-conjugate hemispheres.