scholarly journals Nonlinear generation of the fundamental radiation in plasmas: the influence of induced ion-acoustic and Langmuir waves

1992 ◽  
Vol 48 (1) ◽  
pp. 71-84 ◽  
Author(s):  
F. B. Rizzato ◽  
A. C.-L. Chian
Keyword(s):  
Electromagnetic Waves ◽  
Plasma Frequency ◽  
Low Frequency ◽  
Emission Mechanism ◽  
Langmuir Waves ◽  
Laboratory Plasmas ◽  
Ion Acoustic ◽  
Present Context ◽  
Fundamental Radiation ◽  
Stream Instability

A nonlinear emission mechanism of electromagnetic waves at the fundamental plasma frequency has been examined by Chian & Alves. This mechanism is based on the electromagnetic oscillating two-stream instability driven by two oppositely propagating Langmuir waves. The excitation of the electromagnetic oscillating two-stream instability is due to nonlinear wave–wave coupling involving Langmuir waves, low-frequency density waves and electromagnetic waves. In this paper the Chian & Alves model is improved using the generalized Zakharov equations. Attention is directed toward the influence of induced low-frequency and Langmuir waves on the properties of the electromagnetic oscillating two-stream instability. Presumably, the properties derived in the present context may be relevant to both space and laboratory plasmas.

Multiple-Frequency Measurements of a Flare Continuum Event

1982 ◽  
Vol 4 (4) ◽  
pp. 389-392 ◽  
Author(s):  
R.D. Robinson
Keyword(s):  
Solar Flares ◽  
Electromagnetic Waves ◽  
Plasma Frequency ◽  
Close Association ◽  
Type Ii ◽  
Multiple Frequency ◽  
Langmuir Waves ◽  
Long Duration ◽  
Type Ii Radio Bursts ◽  
The Continuum

A type of metre-wavelength continuum is observed in close association with solar flares and Type II radio bursts. This continuum is stationary in position, often intense, of a long duration (occasionally lasting well over an hour) and highly polarized (Robinson and Smerd 1975; Robinson 1978). It is thought to be produced by the conversion of Langmuir waves to electromagnetic waves near the local plasma frequency. Because of its close association with Type II bursts, the class has been designated as Type II related flare continuum, or FCII. In this paper I examine a particularly clear example of such an event, with emphasis on the relation between the Type II and the start of the continuum.

scholarly journals Oscillating two stream instability of a plasma wave in a negative ion containing plasma with hot and cold positive ions

2007 ◽  
Vol 25 (3) ◽  
pp. 397-406 ◽  
Author(s):  
Hitendra K. Malik
Keyword(s):  
Plasma Wave ◽  
Plasma Frequency ◽  
Low Frequency ◽  
Langmuir Wave ◽  
Negative Ions ◽  
Negative Ion ◽  
Charge Number ◽  
Long Wavelength ◽  
Positive Ions ◽  
Stream Instability

An oscillating two-stream instability (OTSI) is investigated in plasma, which has hot and cold positive ions, negative ions, and the electrons. For this, a long wavelength plasma wave is considered to be driven by two copropagating lasers with frequencies ωL1 and ωL2, such that their difference is almost equal to the electron plasma frequency ωp. In the present mechanism, this plasma beat wave (ωb, kb) is taken to grow in amplitude, so that it becomes susceptible to the OTSI and produces a low frequency electrostatic mode (ω, k), and two shorter wavelength Langmuir wave sidebands (ω1, k1) and (ω2, k2) with ω1 = ω − ωb, ω2 = ω + ωb, k1 = k − kb, and k2 = k + kb in the plasma. The effects of charge number Z, mass, temperature, and density of the ions are studied on the growth rate of the instability, and the amplitudes and phases of the sideband waves generated during the OTSI. It is found that the effects of charge number and mass of the ions are significant on the instability.

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.

Numerical simulations of Zakharov’s (ZK) non-dimensional equation arising in Langmuir and ion-acoustic waves

2021 ◽  
pp. 2150480
Author(s):  
Mostafa M. A. Khater
Keyword(s):  
Acoustic Waves ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Expansion Method ◽  
Ion Acoustic Waves ◽  
B Spline ◽  
Kudryashov Method ◽  
Ion Acoustic ◽  
Dimensional Equation ◽  
The Relationship

The trigonometric quintic B-spline scheme is used in this research paper to research Zakharov’s (ZK) nonlinear dimensional equation’s numerical solution. The ZK model’s solutions explain the relationship between the high-frequency Langmuir and the low-frequency ion-acoustic waves with many applications in optical fiber, coastal engineering, and fluid mechanics of electromagnetic waves, plasma physics, and signal processing. Three recent computational schemes (the expanded [Formula: see text]-expansion method, generalized Kudryashov method, and modified Khater method) have recently been used to investigate this model’s moving wave solution. Many innovative solutions have been established in this paper to determine the original and boundary conditions that allow numerous numerical schemes to be implemented. Here, the trigonometric quintic B-spline method is used to analyze the precision of the collected analytical solutions. To illustrate the precision of the numerical and computational solutions, distinct drawings are depicted.

scholarly journals Mode Conversion and Reflection of Langmuir Waves in an Inhomogeneous Solar Wind

2001 ◽  
Vol 18 (4) ◽  
pp. 355-360 ◽  
Author(s):  
A. J. Willes ◽  
Iver H. Cairns
Keyword(s):  
Solar Wind ◽  
Electromagnetic Waves ◽  
Plasma Frequency ◽  
Mode Conversion ◽  
Langmuir Wave ◽  
Solar Wind Plasma ◽  
Langmuir Waves ◽  
Transverse Electromagnetic ◽  
Solar Wind Parameters ◽  
Conversion Efficiencies

AbstractBeam-driven Langmuir waves in the solar wind are generated just above the electron plasma frequency, which fluctuates in the inhomogeneous solar wind plasma. Consequently, propagating Langmuir waves encounter regions in which the wave frequency is less than the local plasma frequency, where they can be reflected, mode converted to transverse electromagnetic waves, and trapped in density wells. The aim here is to investigate Langmuir wave reflection and mode conversion at a linear density gradient for typical solar wind parameters. It is shown that higher mode conversion efficiencies are possible than previously calculated, but that mode conversion occurs in a smaller region of parameter space. In addition, the possibility of detecting mode conversion with in situ spacecraft Langmuir wave observations is discussed.

scholarly journals On the influence of Langmuir wave spectra on the spectra of electromagnetic waves generated in solar plasma with double plasma frequency

2021 ◽  
Vol 503 (4) ◽  
pp. 5740-5745
Author(s):  
Igor V Kudryavtsev ◽  
T I Kaltman
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Plasma Frequency ◽  
Langmuir Wave ◽  
Wave Spectra ◽  
Langmuir Waves ◽  
Solar Plasma ◽  
Transverse Electromagnetic

ABSTRACT In this paper, we consider the spectral dependences of transverse electromagnetic waves generated in solar plasma at the coalescence of Langmuir waves. It is shown that different spectra of Langmuir waves lead to characteristic types of transversal electromagnetic wave spectra, what makes it possible to diagnose the features of the spectra of Langmuir waves generated in solar plasma.

scholarly journals Particle-in-Cell Simulations of High-Power THz Generator Based on the Collision of Strongly Focused Relativistic Electron Beams in Plasma

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 172
Author(s):  
Vladimir Annenkov ◽  
Evgeny Berendeev ◽  
Evgeniia Volchok ◽  
Igor Timofeev
Keyword(s):  
Electromagnetic Waves ◽  
High Efficiency ◽  
Plasma Frequency ◽  
Electron Beams ◽  
Thz Radiation ◽  
Radiation Mechanisms ◽  
Particle In Cell ◽  
Relativistic Electron Beams ◽  
Nanosecond Pulses ◽  
Stream Instability

Based on particle-in-cell simulations, we propose to generate sub-nanosecond pulses of narrowband terahertz radiation with tens of MW power using unique properties of kiloampere relativistic (2 MeV) electron beams produced by linear induction accelerators. Due to small emittance of such beams, they can be focused into millimeter and sub-millimeter spots comparable in sizes with the wavelength of THz radiation. If such a beam is injected into a plasma, it becomes unstable against the two-stream instability and excites plasma oscillations that can be converted to electromagnetic waves at the plasma frequency and its harmonics. It is shown that several radiation mechanisms with high efficiency of power conversion (∼1%) come into play when the radial size of the beam–plasma system becomes comparable with the wavelength of the emitted waves.

scholarly journals Studies of Spectral Broadening of the Lower Hybrid Wave Line in the Current-Drive Regimes and Ion Heating at the FT-2 Tokamak

2021 ◽  
Vol 47 (4) ◽  
pp. 329-336
Author(s):  
V. V. Dyachenko ◽  
A. B. Altukhov ◽  
E. Z. Gusakov ◽  
L. A. Esipov ◽  
A. N. Konovalov ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Low Frequency ◽  
Current Drive ◽  
Lower Hybrid ◽  
Ion Heating ◽  
Lower Hybrid Wave ◽  
Acoustic Instability ◽  
Ion Acoustic ◽  
Lower Hybrid Current Drive ◽  
High Frequency Waves

Abstract The experiments at the FT-2 tokamak are described that were focused on clearing up the role of the parametric decay instabilities in decreasing the generation efficiency of the non-inductive current excited by the electromagnetic waves in the lower hybrid frequency range. The most discussed instability of such kind is the decay of the pump wave into the daughter high-frequency waves and the low-frequency ion–acoustic quasi-modes. The studies performed have shown that, under conditions of the FT-2 experiment, the ion–acoustic instability has no decisive effect on the decrease in the efficiency of the lower hybrid current drive.

scholarly journals Dust grain dynamics due to nonuniform and nonstationary high-frequency radiations in cold magnetoplasmas

2006 ◽  
Vol 24 (2) ◽  
pp. 467-474 ◽  
Author(s):  
A. K. Nekrasov ◽  
F. Z. Feygin
Keyword(s):  
Electric Fields ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Plasma Parameters ◽  
Laboratory Plasmas ◽  
Background Magnetic Field ◽  
Spatio Temporal ◽  
Dust Grain ◽  
Grain Dynamics

Abstract. A general nonlinear theory for low-frequency electromagnetic field generation due to high-frequency nonuniform and nonstationary electromagnetic radiations in cold, uniform, multicomponent, dusty magnetoplasmas is developed. This theory permits us to consider the nonlinear action of all waves that can exist in such plasmas. The equations are derived for the dust grain velocities in the low-frequency nonlinear electric fields arising due to the presence of electromagnetic cyclotron waves travelling along the background magnetic field. The dust grains are considered to be magnetized as well as unmagnetized. Different regimes for the dust particle dynamics, depending on the spatio-temporal change of the wave amplitudes and plasma parameters, are discussed. It is shown that induced nonlinear electric fields can have both an electrostatic and electromagnetic nature. Conditions for maximum dust acceleration are found. The results obtained may be useful for understanding the possible mechanisms of dust grain dynamics in astrophysical, cosmic and laboratory plasmas under the action of nonuniform and nonstationary electromagnetic waves.

Temporal evolution of reactive and resistive nonlinear instabilities

1987 ◽  
Vol 38 (3) ◽  
pp. 473-481 ◽  
Author(s):  
D. B. Melrose
Keyword(s):  
Electron Number Density ◽  
Temporal Evolution ◽  
Random Phase ◽  
Low Frequency ◽  
Rate Of Change ◽  
Number Density ◽  
Wave Instability ◽  
Langmuir Waves ◽  
Secular Evolution ◽  
Coherent Wave

A kinetic theory for nonlinear processes involving Langmuir waves, developed in an earlier paper, is extended through consideration of three aspects of the temporal evolution, (i) Following Falk & Tsytovich (1975). the dynamic equation for the rate of change of one amplitude at t is expressed as an integral over T of the product of two amplitudes at t – T and a kernel functionf(T); two generalizations of Falk & Tsytovich's form (f(T) ∝ T) that satisfy the requirement f(∞) = 0 are identified, (ii) It is shown that the low-frequency or beat disturbance may be described in terms of fluctuations in the electron number density, and that its time evolution involves an operator that is essentially the inverse of f(t). (iii) The transition from oscillatory evolution in the reactive or ‘coherent-wave’ version of the three-wave instability to the secular evolution of the resistive or ‘random-phase’ version is discussed qualitatively.

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