Effect of parallel electric field on Alfven wave in thermal magnetoplasma

2007 ◽  
Vol 55 (1-2) ◽  
pp. 174-180 ◽  
Author(s):  
P. Varma ◽  
S.P. Mishra ◽  
G. Ahirwar ◽  
M.S. Tiwari
Keyword(s):  
Electric Field ◽  
Alfven Wave ◽  
Parallel Electric Field

scholarly journals Plasma Heating by Alfvén Waves - Kinetic Properties of Magnetohydrodynamic Disturbances

1985 ◽  
Vol 107 ◽  
pp. 381-389
Author(s):  
Akira Hasegawa
Keyword(s):  
Electric Field ◽  
Plasma Heating ◽  
Alfven Wave ◽  
Larmor Radius ◽  
Alfvén Waves ◽  
Kinetic Properties ◽  
Parallel Electric Field ◽  
Astrophysical Plasmas ◽  
Finite Larmor Radius ◽  
Wave Heating

Mechanisms of Alfvén wave heating in space-astrophysical plasmas are presented with particular emphasis on the parallel electric field generated in the magnetohydrodynamic perturbations due to the finite Larmor radius effects.

VLF emission stimulated by parallel electric fields

1985 ◽  
Vol 34 (1) ◽  
pp. 47-66 ◽  
Author(s):  
B. Juhl ◽  
R. A. Treumann
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Electromagnetic Waves ◽  
Resonant Interaction ◽  
Alfven Wave ◽  
Emission Region ◽  
Parallel Electric Field ◽  
Loss Cone ◽  
Excitation Region ◽  
Cone Field

We study the influence of a weak quasi-static parallel electric field on the stability of electromagnetic plasma waves. Using an operator calculus to solve the Boltzmann-Maxwell equations we derive a dispersion relation for the electromagnetic waves. Assuming that the electrons have a loss-cone distribution, the real frequency of waves in the whistler band is not changed by the presence of the electric field. Resonant interaction damps the HF waves for propagation parallel to the electric field. In the case of opposite propagation, a new HF excitation is found at frequencies ω ≲ ωce The width of the excitation region depends on the width of the loss cone, field strength and collision frequency. This result is applied to observations of the splitting of VLF emissions under natural conditions in the magnetosphere. It is found that the observed splitting could have been caused by the presence of the weak parallel electric field of a kinetic (shear) Alfvén wave in the emission region, which is quasi-stationary compared with the growth of the observed VLF emission.

scholarly journals Double layers in the downward current region of the aurora

2003 ◽  
Vol 10 (1/2) ◽  
pp. 45-52 ◽  
Author(s):  
R. E. Ergun ◽  
L. Andersson ◽  
C. W. Carlson ◽  
D. L. Newman ◽  
M. V. Goldman
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Phase Space ◽  
Electric Field ◽  
Electric Fields ◽  
Double Layers ◽  
Parallel Electric Field ◽  
Electrostatic Waves ◽  
Current Region ◽  
Decisive Evidence

Abstract. Direct observations of magnetic-field-aligned (parallel) electric fields in the downward current region of the aurora provide decisive evidence of naturally occurring double layers. We report measurements of parallel electric fields, electron fluxes and ion fluxes related to double layers that are responsible for particle acceleration. The observations suggest that parallel electric fields organize into a structure of three distinct, narrowly-confined regions along the magnetic field (B). In the "ramp" region, the measured parallel electric field forms a nearly-monotonic potential ramp that is localized to ~ 10 Debye lengths along B. The ramp is moving parallel to B at the ion acoustic speed (vs) and in the same direction as the accelerated electrons. On the high-potential side of the ramp, in the "beam" region, an unstable electron beam is seen for roughly another 10 Debye lengths along B. The electron beam is rapidly stabilized by intense electrostatic waves and nonlinear structures interpreted as electron phase-space holes. The "wave" region is physically separated from the ramp by the beam region. Numerical simulations reproduce a similar ramp structure, beam region, electrostatic turbulence region and plasma characteristics as seen in the observations. These results suggest that large double layers can account for the parallel electric field in the downward current region and that intense electrostatic turbulence rapidly stabilizes the accelerated electron distributions. These results also demonstrate that parallel electric fields are directly associated with the generation of large-amplitude electron phase-space holes and plasma waves.

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