Correlation between Ion and Electron Probe Currents in a Turbulent Plasma Flow

1971 ◽  
Vol 49 (9) ◽  
pp. 1114-1119 ◽  
Author(s):  
A. K. Ghosh ◽  
C. Richard ◽  
T. W. Johnston
Keyword(s):  
Electron Density ◽  
Electron Probe ◽  
Plasma Potential ◽  
Density Fluctuations ◽  
Turbulent Plasma ◽  
Temperature Plasma ◽  
Probe Current ◽  
Electron Density Fluctuation ◽  
Ion Probe ◽  
Electron Density Fluctuations

An experimental investigation for the justification of using the electrostatic probes for turbulent plasma diagnostics is discussed. The object is to find how faithfully the probe current fluctuations follow the electron density fluctuations, since in general it is a function of other parameters such as temperature, plasma potential, flow velocity, and gas pressure. The procedure adopted is to study the instantaneous correlation between probes which are close to each other operating in three different modes (single ion probe, single electron probe, and double probe). The probe currents in these three modes will all have the electron density multiplied by expressions differently dependent on other parameters. Excellent instantaneous correlation observed is a persuasive indication that the probe current fluctuation is indeed a measure of the electron density fluctuation. An instantaneous correlation between an ion probe and the floating potential of another probe shows hard diode-type characteristics, the true significance of which is not fully understood.

scholarly journals Imaging electron-density fluctuations by multidimensional X-ray photon-coincidence diffraction

2018 ◽  
Vol 116 (2) ◽  
pp. 395-400 ◽  
Author(s):  
Lyuzhou Ye ◽  
Jérémy R. Rouxel ◽  
Daeheum Cho ◽  
Shaul Mukamel
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Real Space ◽  
Density Fluctuations ◽  
X Ray ◽  
Density Correlation ◽  
Ab Initio Simulations ◽  
Electron Density Fluctuation ◽  
Point Correlation ◽  
Electron Density Fluctuations

The ultrafast spontaneous electron-density fluctuation dynamics in molecules is studied theoretically by off-resonant multiple X-ray diffraction events. The time- and wavevector-resolved photon-coincidence signals give an image of electron-density fluctuations expressed through the four-point correlation function of the charge density in momentum space. A Fourier transform of the signal provides a real-space image of the multipoint charge-density correlation functions, which reveal snapshots of the evolving electron density in between the diffraction events. The proposed technique is illustrated by ab initio simulations of the momentum- and real-space inelastic scattering signals from a linear cyanotetracetylene molecule.

Heterogeneous electron behaviour in a turbulent plasma jet

1973 ◽  
Vol 9 (3) ◽  
pp. 367-375 ◽  
Author(s):  
Anthony Demetriades ◽  
Ernest L. Doughman
Keyword(s):  
Electron Density ◽  
Plasma Jet ◽  
Transitional Zone ◽  
Density Fluctuations ◽  
Turbulent Plasma ◽  
Digital Analysis ◽  
Simple Chemical ◽  
The Mean ◽  
Electron Density Fluctuations ◽  
Growing Population

Uncommonly large electron density fluctuations, accompanied by large skewness and flatness factors, have been observed in the transitional zone of a plasma jet. This paper investigates these further by a digital analysis of Langmuir probe signals from this zone. The electron aggregate is found split into a decaying laminar-fluid remnant and a growing population of turbulent fluid. The uncommon statistics are caused by the double-humped histogram, while those of each population separately are normal. The mean electron density of the aggregate displays no simple chemical decay trend, but that of the laminar population fits known argon recombination schemes.

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.

Pulsars and Interstellar Scintillations

2000 ◽  
Vol 177 ◽  
pp. 539-544
Author(s):  
Y. Gupta
Keyword(s):  
Interstellar Medium ◽  
Electron Density ◽  
Density Fluctuations ◽  
Current Understanding ◽  
Pulsar Emission ◽  
The Galaxy ◽  
Electron Density Fluctuations

AbstractIn this paper, I review our current understanding of interstellar scintillations (ISS) of pulsars. The emphasis is on new results that have appeared during the last five years. The topics covered include (i) review of the understanding of refractive ISS (ii) the shape of the spectrum of electron density fluctuations in the interstellar medium (iii) the distribution of scattering plasma in the Galaxy (iv) resolving pulsar emission regions using ISS and (v) ISS and pulsar velocities.

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