HR: 1340h
AN: SA13A-1467
TI: ELF/VLF Wave Generation with the HAARP Facility
AU: Cohen, M
EM: mcohen@stanford.edu
AF: Stanford University, Stanford, CA, United States
AU: Inan, U S
EM: inan@nova.stanford.edu
AF: Stanford University, Stanford, CA, United States
AU: Golkowski, M
EM: golkowski@stanford.edu
AF: Stanford University, Stanford, CA, United States
AU: Lehtinen, N G
EM: nleht@stanford.edu
AF: Stanford University, Stanford, CA, United States
AU: Piddyachiy, D
EM: depi@stanford.edu
AF: Stanford University, Stanford, CA, United States
AB: The recently upgraded HAARP facility, near Gakona, Alaska, utilizes 3.6 MW of HF (3-10 MHz) power along with an unprecedented ability to steer the HF heating beam over a large area extremely rapidly. In recent decades, HF heating has been successfully utilized to generate ELF/VLF (500 Hz - 10 kHz) radiation, via amplitude modulation of the HF beam. Through the temperature-dependent conductivity of the D-region ionospheric plasma, the lower ionosphere effectively becomes a large radiating antenna in the presence of currents, such as the naturally forming auroral electrojet. A variety of scientific and practical applications would benefit from more effective ability to generate and steer these generated signals, such as magnetospheric injection and study of subsequent wave-particle interactions, ionospheric diagnostics, and long-range communications, especially since additional upgrades to existing HF facilities are difficult. Some recent studies have focused on two particular efforts, known as geometric modulation and beam painting, to boost the generated amplitudes and implement more directional control, using motion of the HF beam. We discuss a set of experimental and theoretical efforts exploring the generation of these ELF/VLF waves, and their coupling to propagating signals in the Earth-ionosphere waveguide and the magnetosphere, utilizing HAARPs upgraded capabilities and an array of ELF/VLF receivers across Alaska. The theoretical formulation utilizes a 3D model of the HF collisional heating and subsequent collisional electron cooling processes, leading to spatial structure of modulated ionospheric conductivities, the results of which are input into an analytical model of ELF/VLF propagation in the Earth-ionosphere waveguide.
DE: [2400] IONOSPHERE
DE: [2403] IONOSPHERE / Active experiments
DE: [2407] IONOSPHERE / Auroral ionosphere
DE: [2494] IONOSPHERE / Instruments and techniques
SC: SPA - Aeronomy (SA)
MN: 2009 Fall Meeting