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Continuous measurement of stimulated electromagnetic emission spectra from HF excited ionospheric turbulence
Author(s) -
Armstrong W. T.,
Massey R.,
Argo P.,
Carlos R.,
Riggin D.,
Cheung P. Y.,
McCarrick M.,
Stanley J.,
Wong A. Y.
Publication year - 1990
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs025i006p01283
Subject(s) - ionosphere , spectral line , physics , excited state , f region , spectral density , computational physics , atomic physics , electromagnetic radiation , emission spectrum , high frequency , turbulence , materials science , optics , geophysics , meteorology , telecommunications , astronomy , computer science
Stimulated electromagnetic emissions of the auroral ionosphere in the vicinity of Fairbanks, Alaska, have been observed during high‐power HF heating experiments. Asymmetric spectra around the heater frequency with dominant lower sidebands are observed under conditions of very long density scale lengths corresponding to f 0 F 1 transition of the heater frequency. Continuous recording of these spectra indicate their strong dependence on controlled cycling of the HF power density and weak dependence on ionospheric fading of the HF wave. Possible physical mechanisms for generating these spectra include stimulated backscattering of the HF pump wave from parametric instabilities and cavitons.