Statistical characteristics of waves in random media with space-time inhomogeneities (review)

Gavrilenko, V. G.; Stepanov, N. S.

doi:10.1007/bf01034070

Cited by 4 publications

(6 citation statements)

References 7 publications

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“…The obtained results are valid for arbitrary propagation distance z. From the obtained result follow, that when dumping is small on the wavelength, but it is rather big on all length of the distance passed by a wave, frequency fluctuations grow much faster, than in the similar medium without absorption [5,15]. This growth continues also outside the layer containing irregularities (at ).…”

Section: Numerical Calculationssupporting

confidence: 59%

“…Now calculate statistical characteristics of scattered electromagnetic waves in an absorptive plasma. Under the usual assumptions of neglecting the depolarization of the field, in the spatialtemporal geometrical optics approximation wave frequency satisfies the stochastic differential transport equation [5,15]:…”

Section: Formulation Of the Problemmentioning

confidence: 99%

“…Right part (3) contains electron density fluctuation , a small parameter which is a measure of the magnitude of the fluctuations of the plasma with zero mean. Equation ( 3) has been derived in the assumption that an unperturbed wave is a plane monochromatic wave propagating along the z-axis, ; the group velocity of an unperturbed wave is directed along the z axis [5,15], c is the local propagation speed of small disturbances of the electron density irregularities. The spectral density function is defined by .…”

Section: Formulation Of the Problemmentioning

confidence: 99%

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Temporal Spectrum of a Scattered Electromagnetic Waves in the Conductive Collision Turbulent Magnetized Plasma

Jandieri¹,

Ishimaru

Rawat

et al. 2022

AEM

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Using WKB method the peculiarities of the temporal spectrum of an ordinary and extraordinary electromagnetic wave scattered in a weakly randomly inhomogeneous three-dimensional nonstationary and conductive magnetized plasma are investigated. On the basis of the stochastic differential transport equation for the frequency fluctuation the broadening and the displacement of the temporal spectrum for both waves are obtained for the polar terrestrial ionosphere. These statistical characteristics contains anisotropic parameters: velocity of a plasma stream, conductivities of the ionosphere, elongated electron density irregularities are characterized by the anisotropy factor and inclination angle with respect to the geomagnetic lines of forces. The analysis of the power spectrum of the waves as a function of the propagation distance and the nondimensional frequency parameter containing the carrier frequency and characteristic temporal scale of electron density fluctuations are carried out. Analytical and numerical calculations have shown that the terrestrial conductivity and anisotropy factors exert a substantial influence on evaluation of the temporal spectrum than the inclination angle. It was found that the wave spectrum increases initially as the square root of the propagation distance, but at large distances it approaches a limiting value. Statistical moments of a scattered ordinary and extraordinary waves do not depend on an absorption sign and valid for both absorptive and active media.

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Section: Numerical Calculationssupporting

confidence: 59%

Section: Formulation Of the Problemmentioning

confidence: 99%

Section: Formulation Of the Problemmentioning

confidence: 99%

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Temporal Spectrum of a Scattered Electromagnetic Waves in the Conductive Collision Turbulent Magnetized Plasma

Jandieri¹,

Ishimaru

Rawat

et al. 2022

AEM

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“…Analyses show that frequency fluctuations grow faster than in nonabsorbing medium given in the studies by Gavrilenko, Kravtsov et al [15,16] if distance travelling by wave in the turbulent plasma exceeds the distance of weak attenuation even at y L > . It is essential to emphasize that second-order statistical moment (9) does not depend on a sign of the parameter 0 ψ .…”

Section: Resultsmentioning

confidence: 85%

“…Neglecting polarization effects, in the geometrical optics approximation, the frequency of the radio wave satisfies the stochastic differential transport equation which is given in the study by Gavrilenko, Kravtsov et al [15,16] for an arbitrary spatial-temporal dispersion:…”

Section: Methodsmentioning

confidence: 99%

Statistical Characteristics of the Temporal Spectrum of Scattered Radiation in the Equatorial Ionosphere

Jandieri

Tugushi

2023

j. of environ. & earth. sci.

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On the basis of the solution of the space-time characteristic system by the method of geometric optics using symbolic calculations, analytical and numerical simulation of the propagation of the ordinary and extraordinary radio waves in the conducting equatorial ionospheric plasma was made considering the anisotropy of plasma irregularities and non-stationary nature of propagation medium. Broadening of the spectrum and the displacement of its maximum contain velocity of a turbulent plasma flow and parameters characterizing anisotropic plasmonic structures. Statistical moments of both radio waves do not depend on the absorption sign and are valid for both active and absorptive random media. Temporal pulsations and conductivity of a turbulent ionospheric plasma have an influence on the evaluation of the spectrum-varying propagation distances travelling by these waves. The new double-humped effect in the temporal spectrum has been revealed for the ordinary wave varying anisotropy coefficient and dip angle of stretched plasmonic structures. From a theoretical point of view, the algorithms developed in this work allow effective modelling of the propagation of both radio signals in the equatorial conductive ionospheric plasma, considering the external magnetic field, inhomogeneities of electron density in-homogeneities, as well as non-stationary.

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Propagation of electromagnetic waves through a turbulent atmosphere

Kravtsov

1992

Rep. Prog. Phys.

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This review covers the major advances achieved in the studies of EM wave propagation in turbulent media for the last two decades with the focus on new physical problems, effects and formalisms., The greatest attention has been directed to the problem of strong fluctuations of intensity. The theoretical results of this treatise include the path integration technique, the predominant correlation method, the two-scale method, the phase approximation in Huygens' method, the hybrid approach to scattering from small inhomogeneities in the presence of large ones, the theory of coherent channels in backscattering, and the concept of partially determinate processes and fields.New physical effects described in the review include the rise of the coherence radius in intermittent turbulence, backscatter enhancement, doubling the variance of phase, incidence angles, group delay, and frequency shifts in the double passage of waves through turbulent media, the residual scintillation effect, the long correlation effect in backscattering, the partial reversal of wavefronts in turbulent media, the magic cap effect in reflection from phase conjugated mirrors, the strong localization of UHF radic waves in stochastic tropospheric waveguides, the effect of penetration in caustic shadow%, and enhanced translucence. New fields of experimental research have been outlined, such as scattering from vegetation and snow covers, and coherent structures in tuibulences, and new objects of theoretical analysis have been elicited: random dislocations of wsvefronts, fractal^ and critical wave phenomena, and the predictability of random fields.

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Statistical characteristics of waves in random media with space-time inhomogeneities (review)

Cited by 4 publications

References 7 publications

Temporal Spectrum of a Scattered Electromagnetic Waves in the Conductive Collision Turbulent Magnetized Plasma

Temporal Spectrum of a Scattered Electromagnetic Waves in the Conductive Collision Turbulent Magnetized Plasma

Statistical Characteristics of the Temporal Spectrum of Scattered Radiation in the Equatorial Ionosphere

Propagation of electromagnetic waves through a turbulent atmosphere

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