scholarly journals Experimental observations of medium and small scale electrostatic waves associated with ionospheric electron density fluctuations

2004 ◽  
Vol 43 (2) ◽  
pp. 173-186
Author(s):  
P. Muralikrishna ◽  
L. P. Vieira ◽  
M. A. Abdu
Keyword(s):  
Electron Density ◽  
Density Fluctuations ◽  
Small Scale ◽  
Ionospheric Electron Density ◽  
Electrostatic Waves ◽  
Electron Density Fluctuations

El 18 de diciembre, 1995 a las 21:17 hrs (TL) se colocaron a bordo de la SONDA III brasileña una prueba de Langmuir yuna de Capacitancia de Alta Frecuencia. Esta sonda fue lanzada desde la estación de lanzamiento de Alcantara (2.31°S; 44.4°W) en Brasil, para realizar mediciones de las variaciones con la altura del campo eléctrico ionosférico y de la densidad electrónica. La nave alcanzó una altitud de 557 km y cubrió un rango horizontal de 589 km. Se operaron desde tierra varios equipos para monitorear las condiciones ionosféricas durante el lanzamiento de modo que la nave alcanzara la región F, donde se presentan las burbujas de plasma. La nave alcanzó la altitud de 557 km y atravesó varias burbujas de plasma de mediano tamaño principalmente en donde se encuentra un perfil downleg de densidad. La densidad electrónica en la parte upleg del perfil mostró la presencia de una muy definida base de la región F alrededor de los 300 km, mientras que el downleg mostró la presencia de un amplio espectro de campo eléctrico e irregularidades en la densidad electrónica y el upleg de la capa F. El análisis espectral de las fluctuaciones en la densidad electrónica y el campo eléctrico indican la presencia de picos espectrales muy definidos a varias alturas que en la mayoría de los casos están asociados unos con otros. Probablemente esto indica la naturaleza electrostática de las ondas eléctricas que se excitan probablemente al inicio de la inestabilidad del plasma junto con las ondas de densidad. Se presentan algunos nuevos resultados de la asociación de estas fluctuaciones con las burbujas de plasma.

scholarly journals Polarimetric Parameters of Scattered Radiation in the Magnetized Plasma

2019 ◽  
Vol 8 (2) ◽  
pp. 77-84
Author(s):  
G. Jandieri ◽  
A. Ishimaru ◽  
J. Pistora ◽  
M. Lesnak
Keyword(s):  
Electron Density ◽  
Electromagnetic Waves ◽  
Density Fluctuations ◽  
Magnetized Plasma ◽  
Stokes Parameters ◽  
Small Scale ◽  
Plasma Slab ◽  
Smooth Perturbation ◽  
Electron Density Fluctuations ◽  
The Relationship

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.

scholarly journals Looking for a proxy of the ionospheric turbulence with Swarm data

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paola De Michelis ◽  
Giuseppe Consolini ◽  
Alessio Pignalberi ◽  
Roberta Tozzi ◽  
Igino Coco ◽  
...  
Keyword(s):  
Electron Density ◽  
Geomagnetic Activity ◽  
Density Fluctuations ◽  
Rate Of Change ◽  
Topside Ionosphere ◽  
Joint Probability Distribution ◽  
Activity Levels ◽  
Scaling Exponents ◽  
Electron Density Fluctuations ◽  
Scaling Features

AbstractThe present work focuses on the analysis of the scaling features of electron density fluctuations in the mid- and high-latitude topside ionosphere under different conditions of geomagnetic activity. The aim is to understand whether it is possible to identify a proxy that may provide information on the properties of electron density fluctuations and on the possible physical mechanisms at their origin, as for instance, turbulence phenomena. So, we selected about 4 years (April 2014–February 2018) of 1 Hz electron density measurements recorded on-board ESA Swarm A satellite. Using the Auroral Electrojet (AE) index, we identified two different geomagnetic conditions: quiet (AE < 50 nT) and active (AE > 300 nT). For both datasets, we evaluated the first- and second-order scaling exponents and an intermittency coefficient associated with the electron density fluctuations. Then, the joint probability distribution between each of these quantities and the rate of change of electron density index was also evaluated. We identified two families of plasma density fluctuations characterized by different mean values of both the scaling exponents and the considered ionospheric index, suggesting that different mechanisms (instabilities/turbulent processes) can be responsible for the observed scaling features. Furthermore, a clear different localization of the two families in the magnetic latitude—magnetic local time plane is found and its dependence on geomagnetic activity levels is analyzed. These results may well have a bearing about the capability of recognizing the turbulent character of irregularities using a typical ionospheric plasma irregularity index as a proxy.

scholarly journals Statistical Measurements of Dispersion Measure Fluctuations of FRBs

2021 ◽  
Vol 922 (2) ◽  
pp. L31
Author(s):  
Siyao Xu ◽  
David H. Weinberg ◽  
Bing Zhang
Keyword(s):  
Electron Density ◽  
Large Scale ◽  
Density Fluctuations ◽  
Clear Correlation ◽  
Dispersion Measure ◽  
Large Dispersion ◽  
Dispersion Measures ◽  
The Difference ◽  
Electron Density Fluctuations ◽  
Scale Turbulence

Abstract Extragalactic fast radio bursts (FRBs) have large dispersion measures (DMs) and are unique probes of intergalactic electron density fluctuations. By using the recently released First CHIME/FRB Catalog, we reexamined the structure function (SF) of DM fluctuations. It shows a large DM fluctuation similar to that previously reported in Xu & Zhang, but no clear correlation hinting toward large-scale turbulence is reproduced with this larger sample. To suppress the distortion effect from FRB distances and their host DMs, we focus on a subset of CHIME catalog with DM < 500 pc cm−3. A trend of nonconstant SF and nonzero correlation function (CF) at angular separations θ less than 10° is seen, but with large statistical uncertainties. The difference found between SF and that derived from CF at θ ≲ 10° can be ascribed to the large statistical uncertainties or the density inhomogeneities on scales on the order of 100 Mpc. The possible correlation of electron density fluctuations and inhomogeneities of density distribution should be tested when several thousands of FRBs are available.

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