Small-scale Alfvén waves localized near an extremum in the finite-amplitude perturbation of the radial plasma density profile

Abstract. We investigate a new mechanism for the formation of a parallel electric field observed in the auroral ionosphere. For this purpose, the excitation of acoustic waves by propagating Alfvén waves was studied numerically. We find that the magnetic pressure perturbation due to finite amplitude Alfvén waves causes the perturbation of the plasma pressure that propagates in the form of acoustic waves, and gives rise to a parallel electric field. This mechanism explains the observations of the strong parallel electric field in the small-scale electromagnetic perturbations of the auroral ionosphere. For the cases when the parallel electric current in the small-scale auroral perturbations is so strong that the velocity of current carriers exceeds the threshold of the ion sound instability, the excited ion acoustic waves may account for the parallel electric fields as strong as tens of mV/m.

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Cluster observations of finite amplitude Alfvén waves and small-scale magnetic filaments downstream of a quasi-perpendicular shock

Journal of Geophysical Research Atmospheres ◽

10.1029/2003ja010056 ◽

2004 ◽

Vol 109 (A5) ◽

Cited By ~ 47

Author(s):

O. Alexandrova

Keyword(s):

Finite Amplitude ◽

Alfven Waves ◽

Alfvén Waves ◽

Small Scale

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Laser-driven ion acceleration from near-critical Gaussian plasma density profile

Laser Acceleration of Electrons, Protons, and Ions VI ◽

10.1117/12.2590785 ◽

2021 ◽

Author(s):

Jan Pšikal

Keyword(s):

Plasma Density ◽

Density Profile ◽

Ion Acceleration ◽

Plasma Density Profile

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Z pinch imploding plasma density profile measurements using a two-frame laser shearing interferometer

IEEE Transactions on Plasma Science ◽

10.1109/tps.2002.1003865 ◽

2002 ◽

Vol 30 (1) ◽

pp. 227-238 ◽

Cited By ~ 23

Author(s):

Niansheng Qi ◽

J. Schein ◽

J. Thompson ◽

P. Coleman ◽

M. McFarland ◽

...

Keyword(s):

Plasma Density ◽

Density Profile ◽

Plasma Density Profile ◽

Z Pinch

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Parametric instabilities of finite-amplitude, circularly polarized Alfvén waves in an anisotropic plasma

Journal of Plasma Physics ◽

10.1017/s0022377800016780 ◽

1993 ◽

Vol 49 (1) ◽

pp. 29-39 ◽

Cited By ~ 1

Author(s):

Hiromitsu Hamabata

Keyword(s):

Finite Amplitude ◽

Alfven Waves ◽

Mhd Equations ◽

Alfvén Waves ◽

Linear Perturbation ◽

Plasma Parameters ◽

Circularly Polarized ◽

Pressure Anisotropy ◽

Parametric Instabilities ◽

Fifth Order

A class of parametric instabilities of finite-amplitude, circularly polarized Alfvén waves in a plasma with pressure anisotropy is studied by application of the CGL equations. A linear perturbation analysis is used to find the dispersion relation governing the instabilities, which is a fifth-order polynomial and is solved numerically. A large-amplitude, circularly polarized wave is unstable with respect to decay into three waves: one sound-like wave and two side-band Alfvén-like waves. It is found that, in addition to the decay instability, two new instabilities that are absent in the framework of the MHD equations can occur, depending on the plasma parameters.

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