Suprathermal electrons in the polar ionosphere

Abstract. Observations by the EISCAT Svalbard radar in summer have revealed electron density enhancements in the magnetic noon sector under conditions of IMF Bz southward. The features were identified as possible candidates for polar-cap patches drifting anti-Sunward with the plasma flow. Supporting measurements by the EISCAT mainland radar, the CUTLASS radar and DMSP satellites, in a multi-instrument study, suggested that the origin of the structures lay upstream at lower latitudes, with the modulation in density being attributed to variability in soft-particle precipitation in the cusp region. It is proposed that the variations in precipitation may be linked to changes in the location of the reconnection site at the magnetopause, which in turn results in changes in the energy distribution of the precipitating particles.Key words: Ionosphere (ionosphere-magnetosphere interactions; plasma temperature and density; polar ionosphere)

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Some Anomalies in the Raman spectrum from laser-produced plasmas

Laser and Particle Beams ◽

10.1017/s0263034600004031 ◽

1988 ◽

Vol 6 (2) ◽

pp. 287-294

Author(s):

T. J. M. Boyd ◽

G. A. Gardner ◽

G. A. Coutts

Keyword(s):

Raman Spectrum ◽

Light Wave ◽

Scattered Light ◽

Thomson Scattering ◽

Hot Electron ◽

Conventional Theory ◽

Suprathermal Electron ◽

Suprathermal Electrons ◽

Scattered Spectrum

Many experiments show features of the Raman spectrum at variance with the predictions of conventional theory. One persistent discrepancy, the cut-off in the spectrum of scattered light at about 1·5λ0, led Simon and Short to postulate that the scattered spectrum is not Raman light as such, but derives from enhanced Thomson scattering from plasmas in which a population of suprathermal electrons is present. We describe a set of simulations which model the propagation of a light wave through a plasma characterized by two electron temperatures with the hot electron fraction varying between 0 and 0·05. The results show that enhanced Thomson scattering will contribute to the spectra observed in some experiments at least and confirm the contention that the spectrum of the scattered light is not especially sensitive to the width of the suprathermal electron feature. We have also examined the effect of a finite quiver velocity on the enhanced Thomson spectrum as a function of the population of suprathermal electrons, in particular its effect on the wavelength bands.

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Effects of ionization and ion loss on dust ion-acoustic solitary waves in a collisional dusty plasma with suprathermal electrons

Physics of Plasmas ◽

10.1063/1.4942935 ◽

2016 ◽

Vol 23 (3) ◽

pp. 033701 ◽

Cited By ~ 3

Author(s):

Saliha Mayout ◽

Leila Ait Gougam ◽

Mouloud Tribeche

Keyword(s):

Dusty Plasma ◽

Solitary Waves ◽

Suprathermal Electrons ◽

Ion Acoustic Solitary Waves ◽

Ion Acoustic

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Electron beam—plasma interaction in a dusty plasma with excess suprathermal electrons

10.1063/1.3659815 ◽

2011 ◽

Cited By ~ 3

Author(s):

A. Danehkar ◽

N. S. Saini ◽

M. A. Hellberg ◽

I. Kourakis ◽

Vladimir Yu. Nosenko ◽

...

Keyword(s):

Electron Beam ◽

Dusty Plasma ◽

Plasma Interaction ◽

Suprathermal Electrons ◽

Beam Plasma ◽

Electron Beam Plasma

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FOUNDATIONS OF THE PERSPECTIVE METHODOLOGY OF COMPLEX STUDIES OF THE INFLUENCE OF AURORAL CHARACTERISTICS OF THE POLAR IONOSPHERE ON THE CONDITIONS OF PROPAGATION OF TRANSPOLAR SIGNALS. REVIEW OF FOREIGN EXPERIMENTS AND RESULTS OF SOME MODELS

Heliogeophysical Research ◽

10.54252/2304-7380_2021_32_3 ◽

2021 ◽

pp. 3-60

Author(s):

A.K. Kuzmin ◽

A.M. Merslyi ◽

O.V. Nikiforov ◽

A.A. Petrukovich ◽

A.M. Sadovsky ◽

...

Keyword(s):

Polar Ionosphere

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Seasonal variations and north–south asymmetries in polar wind outflow due to solar illumination

Annales Geophysicae ◽

10.5194/angeo-34-961-2016 ◽

2016 ◽

Vol 34 (11) ◽

pp. 961-974 ◽

Cited By ~ 4

Author(s):

Lukas Maes ◽

Romain Maggiolo ◽

Johan De Keyser

Keyword(s):

Seasonal Variations ◽

Solar Zenith Angle ◽

The Sun ◽

Polar Ionosphere ◽

Polar Cap ◽

Polar Wind ◽

Simple Set ◽

The Earth ◽

Rotation Of The Earth ◽

Set Up

Abstract. The cold ions (energy less than several tens of electronvolts) flowing out from the polar ionosphere, called the polar wind, are an important source of plasma for the magnetosphere. The main source of energy driving the polar wind is solar illumination, which therefore has a large influence on the outflow. Observations have shown that solar illumination creates roughly two distinct regimes where the outflow from a sunlit ionosphere is higher than that from a dark one. The transition between both regimes is at a solar zenith angle larger than 90°. The rotation of the Earth and its orbit around the Sun causes the magnetic polar cap to move into and out of the sunlight. In this paper we use a simple set-up to study qualitatively the effects of these variations in solar illumination of the polar cap on the ion flux from the whole polar cap. We find that this flux exhibits diurnal and seasonal variations even when combining the flux from both hemispheres. In addition there are asymmetries between the outflows from the Northern Hemisphere and the Southern Hemisphere.

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Plasma properties of suprathermal electrons near comet 67P/Churyumov-Gerasimenko with Rosetta

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834964 ◽

2019 ◽

Vol 630 ◽

pp. A42 ◽

Cited By ~ 6

Author(s):

M. Myllys ◽

P. Henri ◽

M. Galand ◽

K. L. Heritier ◽

N. Gilet ◽

...

Keyword(s):

Solar Wind ◽

Heliocentric Distance ◽

Radial Distance ◽

Hot Electron ◽

Plasma Properties ◽

Measured Velocity ◽

Electron Population ◽

Suprathermal Electrons ◽

Comet 67P ◽

Cometary Activity

Context. The Rosetta spacecraft escorted comet 67P/Churyumov-Gerasimenko from 2014 to September 2016. The mission provided in situ observations of the cometary plasma during different phases of the cometary activity, which enabled us to better understand its evolution as a function of heliocentric distance. Aims. In this study, different electron populations, called warm and hot, observed by the Ion and Electron Sensor (IES) of the Rosetta Plasma Consortium (RPC) are investigated near the comet during the escorting phase of the Rosetta mission. Methods. The estimates for the suprathermal electron densities and temperatures were extracted using IES electron data by fitting a double-kappa function to the measured velocity distributions. The fitting results were validated using observations from other RPC instruments. We give upgraded estimates for the warm and hot population densities compared to values previously shown in literature. Results. The fitted density and temperature estimates for both electron populations seen by IES are expressed as a function of heliocentric distance to study their evolution with the cometary activity. In addition, we studied the dependence between the electron properties and cometocentric distance. Conclusions. We observed that when the neutral outgassing rate of the nucleus is high (i.e., near perihelion) the suprathermal electrons are well characterized by a double-kappa distribution. In addition, warm and hot populations show a significant dependence with the heliocentric distance. The populations become clearly denser near perihelion while their temperatures are observed to remain almost constant. Moreover, the warm electron population density is shown to be strongly dependent on the radial distance from the comet. Finally, based on our results we reject the hypothesis that hot electron population seen by IES consists of solely suprathermal (halo) solar wind electrons, while we suggest that the hot electron population mainly consists of solar wind thermal electrons that have undergone acceleration near the comet.

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