Collisional drift waves in the presences of coherent ion acoustic or Langmuir waves

1971 ◽  
Vol 6 (3) ◽  
pp. 527-540 ◽  
Author(s):  
M. Dobrowolny ◽  
P. Negrini
Keyword(s):  
Acoustic Wave ◽  
Wave Spectrum ◽  
Langmuir Wave ◽  
Drift Waves ◽  
Langmuir Waves ◽  
Ion Acoustic Wave ◽  
Linear Interaction ◽  
Drift Wave ◽  
Ion Acoustic ◽  
The Stability

The dispersion properties of drift waves in a low β weakly collisional plasma, in the presence of ion acoustic or Langmuir waves parallel to magnetic lines, are investigated. It is shown that the non-linear interaction with an ion acoustic wave mainly leads to a shift of the drift wave spectrum towards lower frequencies (and only under very particular conditions affects the stability of the drift wave). The interaction with a Langmuir wave, on the contrary, yields a contribution to the imaginary part of the frequency. The conditions under which this stabilizes unstable drift modes are derived and discussed.

Asymptotic permanent profile of the ion acoustic wave driven by the Langmuir wave

1992 ◽  
Vol 168 (2) ◽  
pp. 120-126 ◽  
Author(s):  
D.J. Kaup ◽  
A. Latifi ◽  
J. Leon
Keyword(s):  
Acoustic Wave ◽  
Langmuir Wave ◽  
Ion Acoustic Wave ◽  
Ion Acoustic

Parametric decay of Langmuir waves in an electron beam-plasma system

1984 ◽  
Vol 31 (3) ◽  
pp. 465-475 ◽  
Author(s):  
Joseph E. Willett ◽  
Yildirim Aktas
Keyword(s):  
Electron Beam ◽  
Acoustic Wave ◽  
Numerical Study ◽  
Low Frequency ◽  
Plasma Electron ◽  
Langmuir Waves ◽  
Ion Acoustic Wave ◽  
Electrostatic Waves ◽  
Beam Plasma ◽  
Ion Acoustic

Backscattering of Langmuir waves from low-frequency electrostatic waves in a plasma traversed by an electron beam is studied. The analysis is based on the use of beam electron, plasma electron, and ion susceptibilities provided by kinetic theory. For the case of a warm electron beam, formulae are derived for the growth rate and threshold associated with resonant backscattering from an ion-acoustic wave modified by the presence of the beam. For the case of a cold electron beam, formulae are derived from the growth rates associated with resonant back-scattering from a modified ion-acoustic wave and from a higher-frequency beam-plasma mode. A numerical study of the effects of an electron beam on these parametric instabilities is included.

Electrostatic parametric resonances in a plasma revisited

1996 ◽  
Vol 55 (3) ◽  
pp. 359-385 ◽  
Author(s):  
J. F. McKenzie ◽  
T. Hagfors
Keyword(s):  
Acoustic Wave ◽  
Dispersion Equation ◽  
Growth Rates ◽  
Fourier Transforms ◽  
Practical Interest ◽  
Langmuir Wave ◽  
Pump Frequency ◽  
Ion Acoustic Wave ◽  
Parametric Resonances ◽  
Ion Acoustic

We generalize Silin's dispersion equation for electrostatic parametric resonances in an unmagnetized plasma to include interactions hitherto overlooked. Of particular interest to ionospheric physicists in this generalization is the interaction between an ion acoustic wave (shifted up in frequency by that of the pump) and an unshifted Langmuir wave. This yields growth rates equal to that of its counterpart in the Silin version, namely the ‘classical’ interaction between a Langmuir wave (shifted down by the pump frequency) and an unshifted ion acoustic wave. The more general (truncated) dispersion equation also displays resonances between ion acoustic sidebands, but this requires pump frequencies of the order of, or less than, the ion plasma frequency and therefore may be of little practical interest in the ionosphere. The system is analysed using Fourier techniques, which lead to two dispersion equations governing the Fourier transforms of the ion and electron perturbation densities. It is shown that, as far as the structure of the coupled recursion relations for the ion and electron Fourier components is concerned, there is an equivalence between the fluid and kinetic treatments. In the case of weak pump fields we calculate the growth rates associated with the various instabilities from a truncated three-wave interaction dispersion relation. Where it is appropriate, these growth rates are compared both with those from the Sum dispersion equation and the counterparts from the Zakharov model. We also discuss the case of very strong pump fields where the ‘natural’ interacting mode frequencies are not those associated with the usual Langmuir—ion acoustic modes of the unpumped plasma, but rather the oscillator frequencies corresponding to the coupled oscillator paradigm that is applicable to the system. Here again we find instabilities of a nature analogous to those arising in the weak pump case.

Theory of double resonance parametric excitation in plasmas. Part 2

1980 ◽  
Vol 24 (2) ◽  
pp. 315-340 ◽  
Author(s):  
Burton D. Fried ◽  
Allen Adler ◽  
Robert Bingham
Keyword(s):  
Acoustic Wave ◽  
Parametric Excitation ◽  
Double Resonance ◽  
Langmuir Wave ◽  
Frequency Separation ◽  
Wave Damping ◽  
Ion Acoustic Wave ◽  
Acoustic Frequency ◽  
Ion Acoustic ◽  
Damping Rate

Using a simpler formalism than in the original paper on this subject, we verify the earlier result that, for a pump frequency separation Δ approximately equal to twice the ion acoustic frequency Ω, the use of two long-wavelength pumps can reduce the threshold for parametric excitation of ion-acoustic waves when, and only when, the Langmuir wave damping rate γ is much larger than Ω. The threshold is then reduced by a factor of order Ω/Ω, the optimum value of t being ▵ 2Ω –Γ for equal pump amplitudes, where Γ is the ion-acoustic wave damping rate and Γ ≪ Ω. The analysis presented in a recent paper is shown to be valid only for γ ≪ Ω, where the threshold reduction is quite small, vanishing in the limit of weak ion-acoustic wave damping (Te/Ti≫ 1).

scholarly journals Ion-Acoustic Instabilities in a Multi-Ion Plasma

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Noble P. Abraham ◽  
Sijo Sebastian ◽  
G. Sreekala ◽  
R. Jayapal ◽  
C. P. Anilkumar ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Acoustic Waves ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
Oxygen Ions ◽  
Ion Plasma ◽  
Thermal Spread ◽  
Ion Acoustic ◽  
Acoustic Instabilities ◽  
The Stability

We have, in this paper, studied the stability of the ion-acoustic wave in a plasma composed of hydrogen, positively and negatively charged oxygen ions, and electrons, which approximates very well the plasma environment around a comet. Modelling each cometary component (H+, O+, and O−) by a ring distribution, we find that ion-acoustic waves can be generated at frequencies comparable to the hydrogen ion plasma frequency. The dispersion relation has been solved both analytically and numerically. We find that the ratio of the ring speed (u⊥s) to the thermal spread (vts) modifies the dispersion characteristics of the ion-acoustic wave. The contrasting behaviour of the phase velocity of the ion-acoustic wave in the presence of O− ions for u⊥s>vts (and vice versa) can be used to detect the presence of negatively charged oxygen ions and also their thermalization.

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