Study of Electron Beam on Electron Cyclotron Waves with AC Field in the Magnetosphere of Uranus

In this paper, we investigate the electromagnetic electron cyclotron (EMEC) waves in the magnetosphere of Uranus. By using the method of characteristic solution, the expression for dispersion relation is drawn. Following kinetic approach, the growth rate and real frequency of EMEC waves is studied theoretically, considering the injection of cold plasma beam in the Uranian system. The observations made by a space probe launched by NASA, Voyager 2, showed unusual orientation of planet’s spin axis and presence of more particles in high energy tail in Uranian magnetospheric plasma. Therefore, in this paper Kappa distribution is employed instead of usual Maxwellian distribution. The study is extended to the parallel as well as the oblique propagation of EMEC waves with variation in temperature anisotropy, number density of electrons and angle of propagation with respect to magnetic field direction. It is found that these parameters support the growth rate of EMEC waves. But response of real frequency of these waves is not same as that of growth rate for all the cases. Numerical analysis also revealed that as the ratio of number density of cold to hot plasma increases growth rate of EMEC waves also increases. Thus, denser the beam is injected, more the growth can be observed. These results are appropriate for applications to space plasma environments and magnetospheric regimes for detailed comparative planetary study.

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ELECTROMAGNETIC ELECTRON-CYCLOTRON WAVES WITH AC FIELD IN THE MAGNETOSPHERE

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v5i2.1938 ◽

2014 ◽

Vol 5 (2) ◽

pp. 757-766 ◽

Cited By ~ 1

Author(s):

Rajbir Kaur ◽

R.S. Pandey ◽

S. Kumar ◽

B.S. Tomar

Keyword(s):

Magnetic Field ◽

Growth Rate ◽

Electron Cyclotron ◽

Field Direction ◽

Magnetic Field Direction ◽

Number Density ◽

Temperature Anisotropy ◽

Ac Field ◽

Electron Cyclotron Waves ◽

Kappa Distribution Function

In this paper the effect of externally injected beam of cold electrons on electromagnetic electron-cyclotron (EMEC) waves in the magnetosphere has been discussed. The investigation is conducted using the methodology of characteristic solution and considering kappa distribution function in the presence of AC field.Â The objective of present study is to examine the variation in growth rate of EMEC waves when temperature anisotropy, magnitude of AC field and number density of energetic particles varies. It is inferred that EMEC waves grow more significantly when propagating oblique to magnetic field direction rather than parallel to magnetic field direction. Also that as the temperature anisotropy and number density of background plasma increases, growth rate of EMEC waves increases.

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Study of Oblique Propagating Whistler Mode Waves in Presence of Parallel DC Electric Field in Magnetosphere of Saturn

Advanced Electromagnetics ◽

10.7716/aem.v6i2.466 ◽

2017 ◽

Vol 6 (2) ◽

pp. 26 ◽

Cited By ~ 1

Author(s):

R. Kaur ◽

R. S. Pandey

Keyword(s):

Growth Rate ◽

Distribution Function ◽

Energy Density ◽

Wave Number ◽

Number Density ◽

Temperature Anisotropy ◽

Loss Cone ◽

Whistler Mode ◽

Whistler Mode Waves ◽

Magnetosphere Of Saturn

In this paper whistler mode waves have been investigated in magnetosphere of Saturn. The derivation for perturbed distribution function, dispersion relation and growth rate have been determined by using the method of characteristic and kinetic approach. Analytical expressions for growth rate and real frequency of whistlers propagating oblique to magnetic field direction are attained. Calculations have been performed at 6 radial distances in plasma sheet region of Saturn’s magnetosphere as per data provided by Cassini. Work has been extended for bi-Maxwellian as well as Loss-cone distribution function. Parametric analysis show that temperature anisotropy, increase in number density, energy density and angle of propagation increases the growth rate of whistler waves along with significant shift in wave number. In case of Loss-cone distribution, increase in growth rate of whistlers is significantly more than for bi-Maxwellian distribution function. Generation of second harmonics can also be seen in the graphs plotted. It is concluded that parallel DC field stabilizes the wave and temperature anisotropy, angle of propagation, number density and energy density of electrons enhances the growth rate. Thus the results are of importance in analyzing observed VLF emissions over wide spectrum of frequency range in Saturnian magnetosphere. The analytical model developed can also be used to study various types of instabilities in planetary magnetospheres.

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Energy Dependent Growth Rates of AIN using Pulsed Supersonic Jets

MRS Proceedings ◽

10.1557/proc-482-319 ◽

1997 ◽

Vol 482 ◽

Author(s):

V. W. Ballarotto ◽

M. E. Kordesch

Keyword(s):

Growth Rate ◽

Kinetic Energy ◽

Film Growth ◽

High Energy ◽

Supersonic Jets ◽

Number Density ◽

Ammonia Gas ◽

Dependent Growth ◽

Energy Dependent

AbstractAIN films were grown on Si< 100 >, using unskimmed pulsed supersonic jets of ammonia and trimethylaluminum (TMA). By seeding the ammonia gas in hydrogen or helium, several different energies of the N precursor were used to examine the effect of N kinetic energy on the growth rate of AIN. The energy of the Al precursor, TMA, was 130 meV in all cases. The highest growth rate (0.115 μm/hr) was achieved with the high energy ammonia jet. The role of number density on film growth is discussed.

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Electron cyclotron waves in the presence of parallel electric fields in the Earth's auroral plasma

Annales Geophysicae ◽

10.1007/s00585-997-0024-3 ◽

1997 ◽

Vol 15 (1) ◽

pp. 24-28 ◽

Cited By ~ 6

Author(s):

S. Kumar ◽

S. K. Dixit ◽

A. K. Gwal

Keyword(s):

Growth Rate ◽

Electric Field ◽

Electric Fields ◽

Electron Cyclotron ◽

Wave Excitation ◽

Parallel Electric Field ◽

Excitation Process ◽

Auroral Plasma ◽

Auroral Electrons ◽

Electron Cyclotron Waves

Abstract. The electron cyclotron waves that originate at low altitudes (<0.5 RE) and observed by ground facilities have been studied in the presence of a weak parallel electric field in auroral magnetoplasma consisting of trapped energetic auroral electrons and cold background electrons of ionospheric origin. The model distribution for auroral trapped electrons is taken as Maxwellian ring distribution. An expression for the growth rate has been obtained in the presence of parallel electric field assuming that the real frequency in the whistler mode is not affected by the presence of the electric field. The results show that waves grow (or damp) in amplitude for a parallel (or antiparallel) electric field. The influence of the electric field is more pronounced at a shorter wavelength spectrum. An increase in population of energetic electrons increases the growth rate and thus, plays a significant role in the wave excitation process in the auroral regions.

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Effects of electron distribution anisotropy in spectroscopic diagnostics of solar flares

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833208 ◽

2018 ◽

Vol 618 ◽

pp. A176 ◽

Cited By ~ 2

Author(s):

E. Dzifčáková ◽

M. Karlický

Keyword(s):

Electron Distribution ◽

High Energy ◽

Maxwellian Distribution ◽

Temperature Anisotropy ◽

Energy Distributions ◽

Ionization Equilibrium ◽

Line Intensities ◽

Relative Line ◽

High Energy Tail ◽

Temperature Diagnostics

Aims. We analyzed effects of the bi-Maxwellian electron distribution representing electron temperature anisotropy along and across the magnetic field on the ionization and excitation equilibrium with consequences on the temperature diagnostics of the flare plasma. Methods. The bi-Maxwellian energy distributions were calculated numerically. Synthetic X-ray line spectra of the bi-Maxwellian distributions were calculated using non-Maxwellian ionization, recombination, excitation and de-excitation rates. Results. We found that the anisotropic bi-Maxwellian velocity distributions transform to the nonthermal energy distributions with a high-energy tail. Their maximum is shifted to lower energies and contains a higher number of the low-energy particles in comparison with the Maxwellian one. Increasing the deviation of the parameter p = T∥/T⊥ from 1, changes the shape of bi-Maxwellian distributions and ionization equilibrium, and relative line intensities also increase. The effects are more significant for the bi-Maxwellian distribution with T∥ > T⊥. Moreover, considering different acceleration mechanisms and collisional isotropization it is possible that the bi-Maxwellian distributions with high deviations from the Maxwellian distribution are more probable for those with p > 1 than for those with p < 1. Therefore, distributions with p > 1 can be much more easily diagnosed than those with p < 1. Furthermore, we compared the effects of the bi-Maxwellian distributions on the ionization equilibrium and temperature diagnostics with those for the κ-distributions obtained previously. We found that they are similar and at the present state it is difficult to distinguish between the bi-Maxwellian and κ-distributions from the line ratios.

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Electromagnetic power of lightning superbolts from Earth to space

Nature Communications ◽

10.1038/s41467-021-23740-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

J.-F. Ripoll ◽

T. Farges ◽

D. M. Malaspina ◽

G. S. Cunningham ◽

E. H. Lay ◽

...

Keyword(s):

Low Frequency ◽

Optical Emission ◽

High Energy ◽

Very Low Frequency ◽

Electromagnetic Power ◽

Power Spectral ◽

High Energy Tail ◽

Van Allen Probes ◽

Long Time ◽

Low Frequency Waves

AbstractLightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space. Superbolt events occurred in 2010-2018 could be localized by extracting the high energy tail of the lightning stroke signals measured by the very low frequency ground stations of the World-Wide Lightning Location Network. Here, we report electromagnetic observations of superbolts from space using Van Allen Probes satellite measurements, and ground measurements, and with two events measured both from ground and space. From burst-triggered measurements, we compute electric and magnetic power spectral density for very low frequency waves driven by superbolts, both on Earth and transmitted into space, demonstrating that superbolts transmit 10-1000 times more powerful very low frequency waves into space than typical strokes and revealing that their extreme nature is observed in space. We find several properties of superbolts that notably differ from most lightning flashes; a more symmetric first ground-wave peak due to a longer rise time, larger peak current, weaker decay of electromagnetic power density in space with distance, and a power mostly confined in the very low frequency range. Their signal is absent in space during day times and is received with a long-time delay on the Van Allen Probes. These results have implications for our understanding of lightning and superbolts, for ionosphere-magnetosphere wave transmission, wave propagation in space, and remote sensing of extreme events.

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