Accession Number : ADA214756

Title :   Oblique Ionospheric Heating and Effects on Radio Propagation.

Descriptive Note : Final rept. May-Sep 87,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Lee, Min-Chang

PDF Url : ADA214756

Report Date : Jun 1989

Pagination or Media Count : 42

Abstract : The process of self focusing of high intensity Gaussian HF electromagnetic beams in the ionosphere is studied. Analytic expressions for threshold intensity, growth rate and focal length are obtained in terms of the beam parameters for self focusing due to the ponderomotive force. Spectral broadening of VLF waves traversing the ionosphere has been studied. Two mechanisms, nonlinear scattering and parametric excitation of lower hybrid waves are shown to provide nonlinear mode conversion of VLF waves into electrostatic plasma modes in the presence of ionospheric density striations. The proposed mechanisms can be tested in an experiment that combines the operation of HF and VLF ionospheric heaters. Keywords: Oblique ionospheric modification. (edc)

Descriptors :   *ELECTROMAGNETIC WAVE PROPAGATION, *IONOSPHERIC MODIFICATION, *RADIO TRANSMISSION, ANALYTIC FUNCTIONS, BROADBAND, ENERGY CONVERSION, DENSITY, ELECTROSTATICS, EXCITATION, FOCUSING, GROWTH(GENERAL), HEATING, HIGH FREQUENCY, HIGH INTENSITY, HYBRID SYSTEMS, INTENSITY, IONOSPHERE, LENGTH, NONLINEAR SYSTEMS, PARAMETERS, PLASMAS(PHYSICS), RATES, ELECTROMAGNETIC SCATTERING, SELF OPERATION, SPECTRA, STRIATIONS, THRESHOLD EFFECTS, VERY LOW FREQUENCY

Subject Categories : Radiofrequency Wave Propagation
      Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE