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 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.

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.

Drift instability in the presence of a parallel electric field and an inhomogeneous magnetic field: particle aspect analysis

1991 ◽  
Vol 46 (1) ◽  
pp. 49-62 ◽  
Author(s):  
M. S. Tiwari ◽  
P. Varma
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Electric Field ◽  
Inhomogeneous Magnetic Field ◽  
Thermal Velocity ◽  
Parallel Electric Field ◽  
Zeroth Order ◽  
Plasma Parameters ◽  
Drift Instability ◽  
Particle Aspect Analysis

The theory of particle aspect analysis is extended to a drift wave in the presence of an inhomogeneous magnetic field and an applied electric field parallel to the ambient magnetic field. The effect of a parallel electric field is included in the zeroth-order distribution function through modification of the particle thermal velocity in that direction. The plasma under consideration is assumed to be anisotropic and with low β. The dispersion relation and growth rate are evaluated and discussed for particular plasma parameters. The limitations of the theory are also pointed out.

scholarly journals Diagnosing collisionless energy transfer using field–particle correlations: Alfvén-ion cyclotron turbulence

2020 ◽  
Vol 86 (4) ◽  
Author(s):  
Kristopher G. Klein ◽  
Gregory G. Howes ◽  
Jason M. TenBarge ◽  
Francesco Valentini
Keyword(s):  
Energy Transfer ◽  
Electric Field ◽  
Transfer Rate ◽  
Velocity Space ◽  
Turbulence Energy ◽  
Correlation Technique ◽  
Parallel Electric Field ◽  
Particle Correlation ◽  
Particle Correlations ◽  
Ion Cyclotron

We apply field–particle correlations – a technique that tracks the time-averaged velocity-space structure of the energy density transfer rate between electromagnetic fields and plasma particles – to data drawn from a hybrid Vlasov–Maxwell simulation of Alfvén-ion cyclotron turbulence. Energy transfer in this system is expected to include both Landau and cyclotron wave–particle resonances, unlike previous systems to which the field–particle correlation technique has been applied. In this simulation, the energy transfer rate mediated by the parallel electric field $E_{\Vert }$ comprises approximately 60 % of the total rate, with the remainder mediated by the perpendicular electric field $E_{\bot }$ . The parallel electric field resonantly couples to protons, with the canonical bipolar velocity-space signature of Landau damping identified at many points throughout the simulation. The energy transfer mediated by $E_{\bot }$ preferentially couples to particles with $v_{tp}\lesssim v_{\bot }\lesssim 3v_{tp}$ , where $v_{tp}$ is the proton thermal speed, in agreement with the expected formation of a cyclotron diffusion plateau. Our results demonstrate clearly that the field–particle correlation technique can distinguish distinct channels of energy transfer using single-point measurements, even at points in which multiple channels act simultaneously, and can be used to determine quantitatively the rates of particle energization in each channel.

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. 

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