IRIS Diagnoses of Man-Made and Naturally-Occurring Ionospheric Plasma Turbulence
Final rept., 1 Aug 2002-28 Feb 2005
MASSACHUSETTS INST OF TECH CAMBRIDGE PLASMA FUSION CENTER
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Radio wave experiments have been conducted at Arecibo, Puerto Rico and Gakona, Alaska together with numerical analyses aimed at investigating man-made and naturally-occurring ionospheric plasma turbulence. Research progress and results reported include the following. 1 Ionospheric ELF and VLF experiments in Alaska discover that a horizontal Hertzian magnetic dipole HMD with a radius of about 7 km at an altitude around 70 km is responsible for the generation of ELFVLF waves. 2 Numerical analyses of ELF and VLF wave generation show that the modulation scheme using the half-wave rectified wave is the most efficient one to generate signals at the modulation frequency and second harmonic, confirming our theoretical predictions. 3 Theoretical study of ionospheric HF heating experiments finds that the dominant factors, determining the number of cascade lines in the radar-detected spectrum of HF enhanced plasma lines HFPLs, include the ion-to-electron temperature ratio, TiTe, the background plasma inhomogeneity scale length, and the heating wave field intensity. 4 The very intense ionospheric plasma turbulence observed over Arecibo, Puerto Rico on December 26, 2004 was possibly triggered by the tsunami-induced gravity waves propagating from Sumatra, Indonesia to Puerto Rico about 23 hours after the occurrence of a Mw 9.2 earthquake.
- Radiofrequency Wave Propagation
- Atmospheric Physics
- Plasma Physics and Magnetohydrodynamics