scholarly journals Beam effect on electromagnetic ion-cyclotron waves with general loss – cone distribution function in an anisotropic plasma-particle aspect analysis

2007 ◽  
Vol 25 (2) ◽  
pp. 557-568 ◽  
Author(s):  
G. Ahirwar ◽  
P. Varma ◽  
M. S. Tiwari
Keyword(s):  
Growth Rate ◽  
Distribution Function ◽  
Ion Beam ◽  
Temperature Anisotropy ◽  
Loss Cone ◽  
Thermal Anisotropy ◽  
Ion Cyclotron ◽  
Electromagnetic Ion Cyclotron Waves ◽  
The Waves ◽  
Emic Waves

Abstract. The effect of upgoing ion beam and temperature anisotropy on the dispersion relation, growth rate, parallel and perpendicular resonant energies, and marginal instability of the electromagnetic ion cyclotron (EMIC) waves, with general loss-cone distribution function, in a low β homogeneous plasma, is discussed by investigating the trajectories of the charged particles. The whole plasma is considered to consist of resonant and non-resonant particles. The resonant particles participate in an energy exchange with the waves, whereas the non-resonant particles support the oscillatory motion of the waves. The effects of the steepness of the loss-cone distribution, ion beam velocity, with thermal anisotropy on resonant energy transferred, and the growth rate of the EMIC waves are discussed. It is found that the effect of the upgoing ion beam is to reduce the energy of transversely heated ions, whereas the thermal anisotropy acts as a source of free energy for the EMIC waves and enhances the growth rate. It is found that the EMIC wave emissions occur by extracting energy of perpendicularly heated ions in the presence of an upflowing ion beam and a steep loss-cone distribution function in the anisotropic magnetoplasma. The effect of the steepness of the loss-cone is also to enhance the growth rate of the EMIC waves. The results are interpreted for EMIC emissions in the auroral acceleration region.

scholarly journals Effect of ion beam on electromagnetic ion cyclotron instability in hot anisotropic plasma-particle aspect analysis

2011 ◽  
Vol 29 (8) ◽  
pp. 1469-1478 ◽  
Author(s):  
S. Patel ◽  
P. Varma ◽  
M. S. Tiwari ◽  
N. Shukla
Keyword(s):  
Growth Rate ◽  
Distribution Function ◽  
Ion Beam ◽  
Anisotropic Plasma ◽  
Loss Cone ◽  
Thermal Anisotropy ◽  
Beam Velocity ◽  
Emic Wave ◽  
Ion Cyclotron ◽  
Particle Aspect Analysis

Abstract. Using the general loss-cone distribution function electromagnetic ion cyclotron (EMIC) instability affected by up going ion beam has been studied by investigating the trajectories of charged particles. The plasma consisting of resonant and non-resonant particles has been considered. It is assumed that the resonant particles participate in energy exchange with the wave, whereas non-resonant particles support the oscillatory motion of the wave. The effect of ion beam velocity on the dispersion relation, growth rate, parallel and perpendicular resonant energy of the EMIC wave with general loss-cone distribution function in hot anisotropic plasma is described by particle aspect approach. The effect of beam anisotropy and beam density on electromagnetic ion cyclotron instabilities is investigated. Growth length is derived for EMIC waves in hot anisotropic plasma. It is found that the effect of the ion beam is to reduce the energy of transversely heated ions, whereas the thermal anisotropy of the background plasma acts as a source of free energy for the EMIC wave and enhances the growth rate. It is observed that ion beam velocity opposite to the wave propagation and its density reduces the growth rate and enhance the reduction in perpendicularly heated ions energy. The effect of ion beam anisotropy on EMIC wave is also discussed. These results are determined for auroral acceleration region. It is also found that the EMIC wave emissions occur by extracting energy of perpendicularly heated ions in the presence of an up flowing ion beam.

Electromagnetic ion-cyclotron instability in low beta plasma with intrinsic Alfven waves

2021 ◽  
Author(s):  
GuanShan Pu ◽  
ChuanBing Wang ◽  
PeiJin Zhang ◽  
Lin Ye
Keyword(s):  
Growth Rate ◽  
Low Frequency ◽  
Alfven Waves ◽  
Qualitative Description ◽  
Alfvén Waves ◽  
Temperature Anisotropy ◽  
Dimensional Parameter ◽  
Positive Effects ◽  
Ion Cyclotron ◽  
Emic Waves

<p>Intrinsic Alfven waves (IAWs) exist pervasively in the solar-terrestrial plasma, which can preferentially heat newborn ions in the direction perpendicular to the ambient magnetic field via non-resonant interactions when the plasma beta is low. The anisotropized newborn ion populations can excite electromagnetic ion-cyclotron (EMIC) instability. Parametric calculations indicate that the lower the plasma beta is, the higher the growth rate, while the growth rate increases with the number density of newborn ions and the intensity of IAWs. The marginal stable surface in three-dimensional parameter space is also calculated, which provides a qualitative description of parametric conditions for instability. We propose that the coupled effects of non-resonant heating by IAWs and EMIC instability could be an effective mechanism for transferring the energy from low-frequency IAWs to EMIC waves with a frequency below the gyrofrequency of the corresponding ion species. Furthermore, the temperature anisotropy of background ions with the same sense has positive effects on the growth of EMIC waves excited by newborn ions.</p>

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

2017 ◽  
Vol 6 (2) ◽  
pp. 26 ◽  
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. 

scholarly journals Electromagnetic ion-cyclotron instability in the presence of a parallel electric field with general loss-cone distribution function - particle aspect analysis

2006 ◽  
Vol 24 (7) ◽  
pp. 1919-1930 ◽  
Author(s):  
G. Ahirwar ◽  
P. Varma ◽  
M. S. Tiwari
Keyword(s):  
Growth Rate ◽  
Distribution Function ◽  
Electric Field ◽  
General Distribution ◽  
Marginal Stability ◽  
Parallel Electric Field ◽  
Loss Cone ◽  
Emic Wave ◽  
Ion Cyclotron ◽  
Particle Aspect Analysis

Abstract. The effect of parallel electric field on the growth rate, parallel and perpendicular resonant energy and marginal stability of the electromagnetic ion-cyclotron (EMIC) wave with general loss-cone distribution function in a low β homogeneous plasma is investigated by particle aspect approach. The effect of the steepness of the loss-cone distribution is investigated on the electromagnetic ion-cyclotron wave. The whole plasma is considered to consist of resonant and non-resonant particles. It is assumed that resonant particles participate in the energy exchange with the wave, whereas non-resonant particles support the oscillatory motion of the wave. The wave is assumed to propagate parallel to the static magnetic field. The effect of the parallel electric field with the general distribution function is to control the growth rate of the EMIC waves, whereas the effect of steep loss-cone distribution is to enhance the growth rate and perpendicular heating of the ions. This study is relevant to the analysis of ion conics in the presence of an EMIC wave in the auroral acceleration region of the Earth's magnetoplasma.

scholarly journals On a nonlinear state of the electromagnetic ion/ion cyclotron instability

2000 ◽  
Vol 7 (3/4) ◽  
pp. 173-177
Author(s):  
M. Cremer ◽  
M. Scholer
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Plasma Sheet ◽  
Large Temperature ◽  
Plasma Sheet Boundary Layer ◽  
Temperature Anisotropy ◽  
Nonlinear Properties ◽  
Cyclotron Instability ◽  
Ion Cyclotron ◽  
The Waves

Abstract. We have investigated the nonlinear properties of the electromagnetic ion/ion cyclotron instability (EMIIC) by means of hybrid simulations (macroparticle ions, massless electron fluid). The instability is driven by the relative (super-Alfvénic) streaming of two field-aligned ion beams in a low beta plasma (ion thermal pressure to magnetic field pressure) and may be of importance in the plasma sheet boundary layer. As shown in previously reported simulations the waves propagate obliquely to the magnetic field and heat the ions in the perpendicular direction as the relative beam velocity decreases. By running the simulation to large times it can be shown that the large temperature anisotropy leads to the ion cyclotron instability (IC) with parallel propagating Alfvén ion cyclotron waves. This is confirmed by numerically solving the electromagnetic dispersion relation. An application of this property to the plasma sheet boundary layer is discussed.

Direct Observational Evidence of the Simultaneous Excitation of Electromagnetic Ion Cyclotron Waves and Magnetosonic Waves by an Anisotropic Proton Ring Distribution

2021 ◽  
Author(s):  
Shangchun Teng ◽  
Nigang Liu ◽  
Qianli Ma ◽  
Xin Tao ◽  
Wen Li
Keyword(s):  
Energetic Electron ◽  
Observational Evidence ◽  
Ion Dynamics ◽  
Frequency Spectra ◽  
Simultaneous Excitation ◽  
Proton Distribution ◽  
Ion Cyclotron ◽  
Electromagnetic Ion Cyclotron Waves ◽  
Generation Mechanisms ◽  
Emic Waves

<p>Magnetosonic (MS) waves and electromagnetic ion cyclotron (EMIC) waves are two important plasma wave modes in the magnetosphere. Previous simulations have shown that both waves could be generated by a ring-like proton distribution, while direct observational evidence has yet to be reported. Here, we present simultaneous observations of MS and EMIC waves and a detailed case analysis. The linear growth rates estimated for both waves are in good agreement with the observed wave frequency spectra. The measured proton distribution evolution is also compared with the simulation results, providing direct observational evidence for the previous theoretical prediction that anisotropic ring-like proton distributions could excite MS and EMIC waves simultaneously. Our findings are crucial for understanding the generation mechanisms of and relation between MS and EMIC waves and for evaluating their combined effects on energetic electron and ion dynamics. </p>

Excitation of ion-cyclotron waves by a spiralling ion beam in a plasma cylinder

1993 ◽  
Vol 50 (2) ◽  
pp. 331-338 ◽  
Author(s):  
S. C. Sharma ◽  
V. K. Tripathi
Keyword(s):  
Growth Rate ◽  
Energy Transfer ◽  
Beam Energy ◽  
Cyclotron Frequency ◽  
Ion Beam ◽  
Harmonic Number ◽  
Plasma Cylinder ◽  
Higher Harmonics ◽  
Ion Cyclotron Waves ◽  
Ion Cyclotron

A helical ion beam propagating through a plasma cylinder drives electrostatic ion-cyclotron waves to instability via cyclotron interaction. Higher harmonics of the beam cyclotron frequency can be generated in this way. The growth rate increases with the harmonic number. The efficiency of beam energy transfer to the wave can be of the order of a few per cent.

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