scholarly journals Ion-acoustic solitary waves and spectrally uniform scattering cross section enhancements

2010 ◽  
Vol 28 (6) ◽  
pp. 1299-1306 ◽  
Author(s):  
J. Ekeberg ◽  
G. Wannberg ◽  
L. Eliasson ◽  
K. Stasiewicz
Keyword(s):  
Solitary Waves ◽  
Acoustic Waves ◽  
Magnetized Plasma ◽  
Ion Acoustic Waves ◽  
Langmuir Waves ◽  
Incoherent Scatter Radars ◽  
Ion Acoustic Solitary Waves ◽  
Ion Acoustic ◽  
Order Of Magnitude ◽  
Thermal Level

Abstract. Spectra measured by incoherent scatter radars are formed predominantly by scattering of the incident signal off ion-acoustic and Langmuir waves in the ionosphere. Occasionally, the upshifted and/or downshifted lines produced by the ion-acoustic waves are enhanced well above thermal levels and referred to as naturally enhanced ion-acoustic lines. In this paper, we study another kind of enhancement, which is spectrally uniform over the whole ion-line, i.e. the up- and downshifted shoulder and the spectral valley in between. Based on observations made with the EISCAT Svalbard radar (ESR) facility, we investigate the transient and spectrally uniform power enhancements, which can be explained by ion-acoustic solitary waves. We use a theory of nonlinear waves in a magnetized plasma to determine the properties of such waves and evaluate their effects on scattered signals measured by ESR. We suggest a new mechanism that can explain backscattered power enhancements by one order of magnitude above the thermal level and show that it is consistent with observations.

scholarly journals Anomalous width variation of rarefactive ion acoustic solitary waves in the context of auroral plasmas

2004 ◽  
Vol 11 (2) ◽  
pp. 219-228 ◽  
Author(s):  
S. S. Ghosh ◽  
G. S. Lakhina
Keyword(s):  
Solitary Waves ◽  
Nonlinear Theory ◽  
Acoustic Waves ◽  
Large Amplitude ◽  
Magnetized Plasma ◽  
Amplitude Variation ◽  
Fully Nonlinear ◽  
Weakly Nonlinear ◽  
Ion Acoustic Solitary Waves ◽  
Ion Acoustic

Abstract. The presence of dynamic, large amplitude solitary waves in the auroral regions of space is well known. Since their velocities are of the order of the ion acoustic speed, they may well be considered as being generated from the nonlinear evolution of ion acoustic waves. However, they do not show the expected width-amplitude correlation for K-dV solitons. Recent POLAR observations have actually revealed that the low altitude rarefactive ion acoustic solitary waves are associated with an increase in the width with increasing amplitude. This indicates that a weakly nonlinear theory is not appropriate to describe the solitary structures in the auroral regions. In the present work, a fully nonlinear analysis based on Sagdeev pseudopotential technique has been adopted for both parallel and oblique propagation of rarefactive solitary waves in a two electron temperature multi-ion plasma. The large amplitude solutions have consistently shown an increase in the width with increasing amplitude. The width-amplitude variation profile of obliquely propagating rarefactive solitary waves in a magnetized plasma have been compared with the recent POLAR observations. The width-amplitude variation pattern is found to fit well with the analytical results. It indicates that a fully nonlinear theory of ion acoustic solitary waves may well explain the observed anomalous width variations of large amplitude structures in the auroral region.

Effect of finite ion-temperature on ion-acoustic solitary waves in an inhomogeneous plasma

1981 ◽  
Vol 59 (6) ◽  
pp. 719-721 ◽  
Author(s):  
Bhimsen K. Shivamoggi
Keyword(s):  
Solitary Wave ◽  
Solitary Waves ◽  
Acoustic Waves ◽  
Inhomogeneous Plasma ◽  
Ion Temperature ◽  
Ion Acoustic Waves ◽  
Weakly Nonlinear ◽  
Ion Acoustic Solitary Waves ◽  
Ion Acoustic ◽  
Velocity Of Propagation

The propagation of weakly nonlinear ion–acoustic waves in an inhomogeneous plasma is studied taking into account the effect of finite ion temperature. It is found that, whereas both the amplitude and the velocity of propagation decrease as the ion–acoustic solitary wave propagates into regions of higher density, the effect of a finite ion temperature is to reduce the amplitude but enhance the velocity of propagation of the solitary wave.

Solitons in ion-beam plasmas bounded by cylindrical geometry

1989 ◽  
Vol 67 (6) ◽  
pp. 609-613 ◽  
Author(s):  
G. C. Das ◽  
KH. Ibohanbi Singh ◽  
B. Karmakar
Keyword(s):  
Solitary Waves ◽  
Acoustic Waves ◽  
Ion Beam ◽  
Ion Beams ◽  
Cylindrical Geometry ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Solitary Waves ◽  
Ion Acoustic ◽  
Bounded Plasma ◽  
Modifying Effect

Nonlinear ion-acoustic solitary waves are studied in a cylindrically bounded plasma consisting of ions and ion beams, along with multiple-temperature electrons, through the derivation of a Korteweg–deVries equation. The interaction of isothermality on the propagation of radially ingoing ion-acoustic waves in various plasmas exerts a drastic modifying effect on the existence and behaviour of the solitons. The results have been compared extensively with those available to date for planar, as well as spherical, solitons.

scholarly journals Effect of Finite Ion Temperature and Modulational Instability of Ion-Acoustic Waves in Presence of an Inhomogeneous Plasma

1985 ◽  
Vol 40 (4) ◽  
pp. 421-424
Author(s):  
Sikha Bhattacharyya ◽  
R. K. Roy Choudhury
Keyword(s):  
Solitary Waves ◽  
Acoustic Waves ◽  
Modulational Instability ◽  
Inhomogeneous Plasma ◽  
Extended Version ◽  
Ion Temperature ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Solitary Waves ◽  
Ion Acoustic ◽  
Frame Work

Using an extended version of K. B. M. method we have investigated the effect of finite ion temperature on ion-acoustic solitary waves. Modulational instability has been discussed in a frame work of nonlinear Schrödinger equation. Some numerical results are also given.

Stability and instability of some nonlinear dispersive solitary waves in higher dimension

1996 ◽  
Vol 126 (1) ◽  
pp. 89-112 ◽  
Author(s):  
Anne de Bouard
Keyword(s):  
Solitary Waves ◽  
Acoustic Waves ◽  
Vries Equation ◽  
Three Dimensional ◽  
Higher Dimension ◽  
Ion Acoustic Waves ◽  
Stability And Instability ◽  
Ion Acoustic ◽  
De Vries ◽  
The Stability

We study the stability of positive radially symmetric solitary waves for a three dimensional generalisation of the Korteweg de Vries equation, which describes nonlinear ion-acoustic waves in a magnetised plasma, and for a generalisation in dimension two of the Benjamin–Bona–Mahony equation.

Stability of ion–acoustic solitary waves in a multi-species magnetized plasma consisting of non-thermal and isothermal electrons

2009 ◽  
Vol 75 (5) ◽  
pp. 593-607 ◽  
Author(s):  
SK. ANARUL ISLAM ◽  
A. BANDYOPADHYAY ◽  
K. P. DAS
Keyword(s):  
Stability Analysis ◽  
Solitary Wave ◽  
Solitary Waves ◽  
Perturbation Expansion ◽  
Magnetized Plasma ◽  
Wave Number ◽  
First Order ◽  
Zk Equation ◽  
Ion Acoustic Solitary Waves ◽  
Ion Acoustic

AbstractA theoretical study of the first-order stability analysis of an ion–acoustic solitary wave, propagating obliquely to an external uniform static magnetic field, has been made in a plasma consisting of warm adiabatic ions and a superposition of two distinct populations of electrons, one due to Cairns et al. and the other being the well-known Maxwell–Boltzmann distributed electrons. The weakly nonlinear and the weakly dispersive ion–acoustic wave in this plasma system can be described by the Korteweg–de Vries–Zakharov–Kuznetsov (KdV-ZK) equation and different modified KdV-ZK equations depending on the values of different parameters of the system. The nonlinear term of the KdV-ZK equation and the different modified KdV-ZK equations is of the form [φ(1)]ν(∂φ(1)/∂ζ), where ν = 1, 2, 3, 4; φ(1) is the first-order perturbed quantity of the electrostatic potential φ. For ν = 1, we have the usual KdV-ZK equation. Three-dimensional stability analysis of the solitary wave solutions of the KdV-ZK and different modified KdV-ZK equations has been investigated by the small-k perturbation expansion method of Rowlands and Infeld. For ν = 1, 2, 3, the instability conditions and the growth rate of instabilities have been obtained correct to order k, where k is the wave number of a long-wavelength plane-wave perturbation. It is found that ion–acoustic solitary waves are stable at least at the lowest order of the wave number for ν = 4.

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