E. J. Kennedy

ELF waves generated by modulated HF heating of the auroral electrojet and observed at a ground distance of 4400 km

[1] We present calibrated measurements of ELF waves generated by modulated HF heating of the auroral electrojet by the High frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska, and detected after propagating more than 4400 km in the Earth-ionosphere waveguide to Midway Atoll. The magnitude of the 2125 Hz wave received at Midway Atoll is consistent with the radiation from a horizontal dipole located at the altitude of the maximum Hall conductivity variation (created by modulated HF heating) and radiating � 4–32 W. The HF-ELF conversion efficiency at HAARP is thus estimated to be � 0.0004–0.0032% for the 2125 Hz wave generated using sinusoidal amplitude modulation.

Subionospheric VLF observations of transmitter‐induced precipitation of inner radiation belt electrons

[1] Ionospheric effects of energetic electron precipitation induced by controlled injection of VLF signals from a ground based transmitter are observed via subionospheric VLF remote sensing. The 21.4 kHz NPM transmitter in Lualualei, Hawaii is keyed ON-OFF in 30 minute periodic sequences. The same periodicity is observed in the amplitude and phase of the sub ionospherically propagating signals of the 24.8 kHz NLK (Jim Creek, Washington) and 25.2 kHz NLM (LaMoure, North Dakota) transmitters measured at Midway Island. Periodic perturbations of the NLK signal observed at Palmer, Antarctica suggest that energetic electrons scattered at longitudes of NPM continue to be precipitated into the atmosphere as they drift toward the South Atlantic Anomaly. Utilizing a model of the magnetospheric waveparticle interaction, ionospheric energy deposition, and subionospheric VLF propagation, the precipitated energy flux induced by the NPM transmitter is estimated to peak at

The WIND‐HAARP Experiment: Initial results of high power radiowave interactions with space plasmas

Results from the first science experiment with the new HF Active Auroral Research Program (HAARP) in Alaska are reported. The objective was to study the effects of space plasmas on high power radiowave transmission to high altitudes in the magnetosphere. Reception was done by the NASA/WIND satellite. The data suggest that structured space plasmas along the propagation path impose a power law spectrum of fluctuations on the transmitted waves, resembling scintillations. Because the transmitted waves are near ionospheric plasma frequencies, other types of wave-plasma interactions may occur. Such measurements can provide a new diagnostic tool.

A wave interference experiment with HAARP, HIPAS, and WIND

We report on the first experiment using two high power, high frequency transmitting facilities in a bistatic, interferometer mode. The HAARP and HIPAS facilities in Alaska radiated at 4525 kHz with total combined power of about 700 kW, in the direction of the WIND spacecraft. The WAVES experiment aboard WIND received the transmissions at a distance of about 25 earth radii. The experimental setup thus resembled Youngs two-slit experiment. The expected interference pattern was observed; at the distance of WIND, the fringe size was about 30 km peak to peak.

High frequency radar astronomy with HAARP

At high frequency, radio waves will interact with space plasmas and surfaces of local astronomical objects, producing an echo that can provide new diagnostic data. The availability at high power radars operating at high frequencies opens a window for the remote investigation of our surrounding space environment. We discuss and illustrate this technique with some specific examples.