HR: 0800h
AN: SA51A-03    [Abstracts]
TI: Artificial Generation of ULF Waves in the Pc1 Range Using the HAARP Heater
AU: * Chang, C
EM: chia-lie.chang@baesystems.com
AF: BAE Systems, 1250 24th Street, NW, Washington DC, DC 20037, United States
AU: Wallace, T
EM: tom.wallace@baesystems.com
AF: BAE Systems, 1250 24th Street, NW, Washington DC, DC 20037, United States
AU: Milikh, G
EM: milikh@astro.umd.edu
AF: Dept. of Physics & Astronomy, University of Maryland , College Park, MD 20742, United States
AU: Papadopoulos, D
EM: kp@astro.umd.edu
AF: Dept. of Physics & Astronomy, University of Maryland , College Park, MD 20742, United States
AB: Artificial generation of ULF waves in the Pc1 frequency range by modulation of the auroral electrojet current using the HAARP heater is reported. The results complement previous experiments using the EISCAT heater (Maul et al., Ann. Geophys. 8, 765, 1990) by including the .1-.7 Hz frequency range that was not covered in previous experiments. The experiments were performed during the period 4/ 27-5/6, 2006. The artificial ULF signals were recorded by a pair of induction magnetometers aligned with NS and EW directions. The measurement site, 12 km northwest of the heating facility, was directly below the modified ionosphere region. The measured amplitudes of the artificial ULF signals were in the range of 10 fT to several pT and comparable in amplitude and polarization to the ones generated by VLF modulation at 1 kHz, interspersed with the ULF modulation. In addition to coherent narrowband ULF waves intensification of the broadband noise between .5-5 Hz by more than 20 dB correlated with HAARP turn-on was observed on the evening of May 5, potentially indicating triggering or amplification of the Alfven- Ion Cyclotron instability in the magnetosphere. In addition to the experimental results the paper will present a theoretical analysis for generating magnetosonic waves by modulated collisionless F- region heating and injecting them efficiently into the Alfvenic duct. The potential for such a source in resolving the long standing issues related to the Alfvenic duct properties (attenuation, group and phase velocities, preferred travel directions, day-night variability, frequency cut-off, etc) will be discussed along with planned experimental tests using the completed HAARP heater at 3.6 MW.
DE: 2403 Active experiments
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2455 Particle precipitation
DE: 2471 Plasma waves and instabilities (2772)
DE: 2487 Wave propagation (0689, 3285, 4275, 4455, 6934)
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly