Magnetospheric Wave-Particle Interactions Excited by the HAARP HF Heater

ELF/VLF wave generation by heated modulation of the ionospheric auroral electrojet currents is used for controlled magnetospheric wave injection experiments. The High Frequency Active Auroral Research Program (HAARP) facility in Alaska is used to efficiently generate electromagnetic radiation in the 500 Hz - 5 kHz frequency range. Electromagnetic waves are injected into the magnetosphere where they experience a wave-particle interaction with radiation belt electrons which is manifested in temporal growth of 15 dB/sec and non-linear triggering of magnetospheric emissions. Amplified and triggered waves called 'echoes' are observed on the ground at both ends of the magnetic field line and also on the DEMETER satellite. Results are presented both for the original 960 kW HAARP array and the recently upgraded 3.6 MW facility. The observations show that observations of HAARP excited magnetospheric amplification are correlated primarily with geomagnetic conditions but are also heavily dependant on the specific frequency-time formats of the injected ELF/VLF radiation. All cases of observed echoes are shown to propagate inside of the plasmapause and show only weak correlation to the local ELF/VLF signal strength. Echo activity is limited to active frequency bands with widths of ~ 1kHz. The echoes are injected into the magnetosphere primarily directly over the heater.