scholarly journals Statistical Moments and Scintillation Level of Scattered Electromagnetic Waves in the Magnetized plasma

2018 ◽  
Vol 7 (3) ◽  
pp. 1-10 ◽  
Author(s):  
G. V. Jandieri ◽  
A. Ishimaru ◽  
B. Rawat ◽  
V. Gavrilenko ◽  
O. Kharshiladze

Statistical characteristics of scattered ordinary and extraordinary electromagnetic waves in the magnetized plasma are considered using the smooth perturbation method. Diffraction effects and polarization coefficients are taken into account. Second order statistical moments of scattered radiation are obtained for arbitrary correlation function of electron density fluctuations. Broadening of the spatial power spectrum and displacement of its maximum, wave phase structure function and the angle-of-arrivals are obtained for three-dimensional spectral function containing anisotropic Gaussian and power-law spectral functions. Scintillation level of scattered radiation is analyzed for different parameters characterizing anisotropic plasma irregularities for the ionospheric F-region. The spectral widths (first and second moments) of the power spectrum and scintillation periods are calculated for “frozen-in” drifting elongated plasma irregularities using the experimental data.

2020 ◽  
Author(s):  
Giorgi Jandieri ◽  
Akira Ishimaru ◽  
Jaromir Pistora

<p>The ionosphere is greatly influenced by ionizing radiation including both electromagnetic flux and energetic particles. The ionosphere is immersed in a magnetic field and the interactions of radio waves with the ionosphere are complex and exhibit the following properties: anisotropy, absorption, dispersion, birefringent. The ionospheric effects on radiowave systems depend upon the focus of the treatment. The development of inhomogeneous electron density structures is responsible for radiowave signal fluctuations. A comprehensive treatment of radiowaves propagation in the ionospheric plasma is based on the investigation of the statistical moments of both amplitude and phase fluctuations of scattered radiation. In this paper analytical calculations of the statistical characteristics in the conductive collision magnetized ionospheric plasma have been carried out for the first time using the complex geometrical optics approximation. Stochastic wave equation of the phase fluctuations includes both dielectric permittivity and conductivity tensors which are random functions of the spatial coordinates and time. Using the boundary conditions correlation function of the phase fluctuations has been obtained for arbitrary second order statistical moment of electron density fluctuations (large and small ionospheric plasmonic structures); observation points are spaced at small distance. The index of refraction contains both ordinary and extraordinary waves. Angular power spectrum (broadening, shift of its maximum) of scattered electromagnetic waves is investigated. It was shown that Hall’s, Pedersen, and longitudinal conductivities have a substantial influence on the frequency fluctuation of an incident wave. Doppler spread associated with random ionospheric structure, and Doppler shifts associated with relative motion of the ray path with respect to the elongated plasmonic structures. Spatial-temporal broadening of the spatial spectrum depends on the anisotropy factor of elongated plasma irregularities, inclination angle with respect to the lines of forces of geomagnetic field, collision frequency between plasma particles, conductivity fluctuations, and the movement of ionospheric plasmonic irregularities. Shift of the spectral maximum changes the sign depending on the anisotropy factor of elongated plasma irregularities, inclination angle with respect to the lines of forces of geomagnetic field and conductivity fluctuations. Numerical calculations and spatial-temporal modeling are carried out for both large and small-scale ionospheric plasma irregularities using experimental data and experimentally observing power-law spectrum of electron density fluctuations. The obtained results are useful for solving the reverse problem restoring plasma parameters, in satellite communication and navigation systems that operate in the earth-space regime. The influence of the conductivity fluctuations on the second order statistical moments will open new horizons in understanding and forecasting new phenomena in the upper ionosphere caused due to spatial-temporal parameters fluctuations.</p><p> </p>


2019 ◽  
Vol 8 (2) ◽  
pp. 77-84
Author(s):  
G. Jandieri ◽  
A. Ishimaru ◽  
J. Pistora ◽  
M. Lesnak

Second order statistical moments of scattered electromagnetic waves in the turbulent magnetized plasma slab with electron density fluctuations are calculated applying the modify stochastic smooth perturbation theory and the boundary conditions. The obtained results are valid for arbitrary correlation function of electron density fluctuations. Stokes parameters are analyzed both analytically and numerically. The theory predicts that depolarization effect caused by second Stokes parameter may be important in scintillation effects. Numerical calculations are carried out for new spectral function of electron density fluctuations containing both anisotropic Gaussian and power-law spectral functions using the experimental data. Polarimetric parameters are calculated for different anisotropy factor and inclination angle of elongated small-scale irregularities with respect to the magnetic lines of forces. The relationship between the scintillations and the polarimetric parameters is important.


1990 ◽  
Vol 43 (2) ◽  
pp. 165-172 ◽  
Author(s):  
V. N. Pavlenko ◽  
V. G. Panchenko

Fluctuations and scattering of transverse electromagnetic waves by density fluctuations in a magnetized plasma in the presence of parametric decay of the pump wave are investigated. The spectral density of electron-density fluctuations is calculated. It is shown that the differential scattering cross-section has sharp maxima at the ion-acoustic and lower-hybrid frequencies when parametric decay of the lower-hybrid pump wave occurs. We note that scattering at the ion-acoustic frequency is dominant. When the pump-wave amplitude tends to the threshold strength of the electric field the scattering cross-section increases anomalously, i.e. there is critical opalescence.


2018 ◽  
Vol 84 ◽  
pp. 11-22 ◽  
Author(s):  
George Jandieri ◽  
Akira Ishimaru ◽  
Banmali Rawat ◽  
Vladimir George Gavrilenko ◽  
Oleg Kharshiladze

2009 ◽  
Vol 76 (2) ◽  
pp. 183-191 ◽  
Author(s):  
DASTGEER SHAIKH ◽  
G. P. ZANK

AbstractObservations of interstellar scintillations at radio wavelengths reveal a Kolmogorov-like scaling of the electron density spectrum with a spectral slope of −5/3 over six decades in wavenumber space. A similar turbulent density spectrum in the solar wind plasma has been reported. The energy transfer process in the magnetized solar wind plasma over such extended length scales remains an unresolved paradox of modern turbulence theories, raising the especially intriguing question of how a compressible magnetized solar wind exhibits a turbulent spectrum that is a characteristic of an incompressible hydrodynamic fluid. To address these questions, we have undertaken three-dimensional time-dependent numerical simulations of a compressible magnetohydrodynamic fluid describing super-Alfvénic, supersonic and strongly magnetized plasma. It is shown that the observed Kolmogorov-like (−5/3) spectrum can develop in the solar wind plasma by supersonic plasma motions that dissipate into highly subsonic motion that passively convect density fluctuations.


2011 ◽  
Vol 20 (10) ◽  
pp. 2115-2119
Author(s):  
WILL J. PERCIVAL

Galaxy Redshift surveys provide a three-dimensional map of the Universe. Three distinct processes that encode cosmological information in these maps, are commonly used to constrain models: (i) the comoving power spectrum shape depends on the physical properties of the early Universe, including the physical matter, baryon and neutrino densities, the inflation power spectrum and the degree of Gaussianity of density fluctuations; (ii) we can use the statistical clustering of galaxies as a standard ruler by matching it, or parts of it at different redshifts, and to the Cosmic Microwave Background (CMB); (iii) redshift-space distortions, anisotropic patterns caused by peculiar galaxy velocities, reveal structure growth. Following the design of my talk at the 1st Galileo–Xu Guangqi Meeting, I will use these proceedings to briefly review these experiments.


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