Solitary Langmuir waves in two-electron temperature plasma

2013 ◽  
Vol 80 (3) ◽  
pp. 405-415
Author(s):  
V. V. Prudkikh
Keyword(s):  
Electron Temperature ◽  
Acoustic Waves ◽  
Low Frequency ◽  
Langmuir Wave ◽  
Wave Interaction ◽  
Plasma Parameters ◽  
Temperature Plasma ◽  
Langmuir Waves ◽  
Peak Structure ◽  
Langmuir Soliton

Nonlinear interaction of Langmuir and ion-acoustic waves in two-electron temperature plasma is investigated. New integrable wave interaction regime was discovered, this regime corresponds to the Langmuir soliton with three-hump amplitude, propagating with a speed close to the ion–sound speed in the conditions of strong non-isothermality of electronic components. It was discovered that besides the known analytical solution in the form of one- and two-hump waves, there exists a range of solutions in the form of solitary waves, which in the form of envelope has multi-peak structure and differs from the standard profiles described by hyperbolic functions. In case of fixed plasma parameters, different group velocities correspond to the waves with different number of peaks. It is found that the Langmuir wave package contains both even and uneven numbers of oscillations. Low-frequency potential here has uneven number of peaks. Interrelation of obtained and known earlier results are also discussed.

Scattering of electromagnetic waves by hybrid waves in a two-electron-temperature plasma

1991 ◽  
Vol 46 (1) ◽  
pp. 99-106 ◽  
Author(s):  
S. K. Sharma ◽  
A. Sudarshan
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Stimulated Scattering ◽  
Coupled Modes ◽  
Temperature Plasma ◽  
Electrostatic Perturbation

In this paper, we use the hydrodynamic approach to study the stimulated scattering of high-frequency electromagnetic waves by a low-frequency electrostatic perturbation that is either an upper- or lower-hybrid wave in a two-electron-temperature plasma. Considering the four-wave interaction between a strong high-frequency pump and the low-frequency electrostatic perturbation (LHW or UHW), we obtain the dispersion relation for the scattered wave, which is then solved to obtain an explicit expression for the growth rate of the coupled modes. For a typical Q-machine plasma, results show that in both cases the growth rate increases with noh/noc. This is in contrast with the results of Guha & Asthana (1989), who predicted that, for scattering by a UHW perturbation, the growth rate should decrease with increasing noh/noc.

Nonlinear interaction of electron acoustic waves with Langmuir waves in presence of magnetic field in plasmas

2014 ◽  
Vol 81 (1) ◽  
Author(s):  
Manjistha Dutta ◽  
Manoranjan Khan ◽  
Nikhil Chakrabarti
Keyword(s):  
Magnetic Field ◽  
Nonlinear Interaction ◽  
Acoustic Waves ◽  
Low Frequency ◽  
Acoustic Mode ◽  
Magnetized Plasma ◽  
Langmuir Waves ◽  
Coupled Equations ◽  
Electron Acoustic Wave ◽  
Electron Acoustic

Nonlinear interaction between Langmuir waves and Electron Acoustic Wave (EAW) is being studied in a warm magnetized plasma in presence of two intermingled fluids, hot electrons, and cold electrons while ions forming static background. Two-fluid, two-timescale theory is performed to derive modified Zakharov's equations in a magnetized plasma. These coupled equations describe low-frequency response of electron density due to high-frequency electric field along with magnetic field perturbations. Linear analysis shows coupling between acoustic mode, upper hybrid mode, and cyclotron modes. These modes are found to be modified due to the presence of two electron components. These equations are significant in the context of weak and strong turbulence.

Coupled Langmuir and nonlinear ion acoustic waves in the presence of non-thermal electrons

2009 ◽  
Vol 75 (2) ◽  
pp. 193-202 ◽  
Author(s):  
H. ALINEJAD ◽  
P. A. ROBINSON ◽  
O. SKJAERAASEN ◽  
I. H. CAIRNS
Keyword(s):  
Mach Number ◽  
Acoustic Waves ◽  
High Frequency ◽  
Strong Field ◽  
Low Frequency ◽  
Thermal Electron ◽  
Electrostatic Waves ◽  
Envelope Solitons ◽  
Langmuir Soliton ◽  
Langmuir Solitons

AbstractA new set of equations describing the coupling of high-frequency electrostatic waves with ion fluctuations is obtained taking into account a non-thermal electron distribution. It is shown that there exist stationary envelope solitons which have qualitatively different structures from the solutions reported earlier. In particular, the Langmuir field envelopes are found with similar width and strong field intensities in comparison to the isothermal case. It is also shown that the presence of the fast or non-thermal electrons significantly modifies the nature of Langmuir solitons in the transition from a single-hump solution to a double-hump solution as the Mach number increases to unity. The low-frequency electrostatic potential associated with the high-frequency Langmuir field has the usual single-dip symmetric structure whose amplitude increases with increasing Mach number. Furthermore, the dip at the center of the double-hump Langmuir soliton is found to become smaller as the proportion of non-thermal electrons increases.

scholarly journals Low frequency waves in plasmas with spatially varying electron temperature

2000 ◽  
Vol 18 (12) ◽  
pp. 1613-1622 ◽  
Author(s):  
P. Guio ◽  
S. Børve ◽  
H. L. Pécseli ◽  
J. Trulsen
Keyword(s):  
Numerical Simulation ◽  
Electron Temperature ◽  
Acoustic Waves ◽  
Low Frequency ◽  
Plasma Temperature ◽  
Electrostatic Waves ◽  
Radio Science ◽  
Particle In Cell ◽  
Ionosphere Plasma ◽  
Low Frequency Waves

Abstract. Low frequency electrostatic waves are studied in magnetized plasmas with an electron temperature which varies with position in a direction perpendicular to the magnetic field. For wave frequencies below the ion cyclotron frequency, the waves need not follow any definite dispersion relation. Instead a band of phase velocities is allowed, with a range of variation depending on the maximum and minimum values of the electron temperature. Simple model equations are obtained for the general case which can be solved to give the spatial variation of a harmonically time varying potential. A simple analytical model for the phenomenon is presented and the results are supported by numerical simulations carried out in a 2½-dimensional particle-in-cell numerical simulation. We find that when the electron temperature is striated along B0 and low frequency waves (ω ≪ Ωci) are excited in this environment, then the intensity of these low frequency waves will be striated in a manner following the electron temperature striations. High frequency ion acoustic waves (ω ≫ Ωci) will on the other hand have a spatially more uniform intensity distribution.Key words: Ionosphere (plasma temperature and density) · Radio science (waves in plasma) · Space plasma physics (numerical simulation studies)

Ulysses Observations of Nonlinear Wave-wave Interactions in the Source Regions of Type III Solar Radio Bursts

2000 ◽  
Vol 179 ◽  
pp. 447-450
Author(s):  
G. Thejappa ◽  
R. J. MacDowall
Keyword(s):  
Acoustic Waves ◽  
Modulational Instability ◽  
Langmuir Wave ◽  
Wave Interactions ◽  
Burst Source ◽  
Langmuir Waves ◽  
Type Iii ◽  
Source Regions ◽  
Ion Acoustic ◽  
Solar Type

AbstractThe Ulysses Unified Radio and Plasma Wave Experiment (URAP) has observed Langmuir, ion-acoustic and associated solar type III radio emissions in the interplanetary medium. Bursts of 50–300 Hz (in the spacecraft frame) electric field signals, corresponding to long-wavelength ion-acoustic waves are often observed coincident in time with the most intense Langmuir wave spikes, providing evidence for the electrostatic decay instability. Langmuir waves often occur as envelope solitons, suggesting that strong turbulence processes, such as modulational instability and soliton formation, often coexist with weak turbulence processes, such as electrostatic decay, in a few type III burst source regions.

Modulational instability of obliquely modulated ionacoustic waves in a two-electron-temperature plasma

1985 ◽  
Vol 33 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Yashvir ◽  
T. N. Bhatnagar ◽  
S. R. Sharma
Keyword(s):  
Electron Temperature ◽  
Acoustic Waves ◽  
Modulational Instability ◽  
Perturbation Technique ◽  
Collisionless Plasma ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Ion Acoustic Waves ◽  
Temperature Plasma ◽  
Damping Rate

The unstable domain in the (k, Ø) plane for oblique modulation of ion-acoustic waves, in a two-electron-temperature plasma, is investigated using the KBM perturbation technique. It is shown that, in a collisionless plasma, the maximum growth rate for the modulational instability, for large carrier-wave amplitudes (a0 ≳ 0·1), exceeds the electron Landau damping rate for sufficiently oblique modulation.

scholarly journals Solar Radar Observations

1980 ◽  
Vol 91 ◽  
pp. 135-138
Author(s):  
A. O. Benz
Keyword(s):  
Specular Reflection ◽  
Beat Frequency ◽  
Langmuir Wave ◽  
Wave Interaction ◽  
Corner Reflector ◽  
The Sun ◽  
Langmuir Waves ◽  
Radar Observations ◽  
Upper Limit ◽  
First Results

Radar observations of the sun have been made extensively at decameter and low meter wavelengths (Eshleman et al., 1960, and James, 1966). Their interpretation by specular reflection on high density structures with “corner reflector” shape is unlikely from the echo spectral broadening and range depth. Gordon's (1973) interpretation of the scattering by a 4 wave interaction between radar and coronal Langmuir waves requires a level of 10−2nKT (thermal energy density) of the Langmuir waves. A radar experiment in microwaves with the 300 m dish in Arecibo*) is described, which was able to test this hypothesis. It was based on the idea of scattering radar waves on Langmuir waves by the much more efficient 3 wave interaction. The echo at the beat frequency of the radar (2380 MHz) and the Langmuir wave (170 −270 MHz) is then to be expected at 2600 MHz. The results, however, show the absence of echos, from which an upper limit of 6.10−4nKT for the level of Langmuir waves is derived. First results will soon be published (Benz and Fitze, 1979).

Propagation of Ion-Acoustic Waves in a Two-Electron-Temperature Plasma

1975 ◽  
Vol 35 (20) ◽  
pp. 1349-1352 ◽  
Author(s):  
W. D. Jones ◽  
A. Lee ◽  
S. M. Gleman ◽  
H. J. Doucet
Keyword(s):  
Electron Temperature ◽  
Acoustic Waves ◽  
Ion Acoustic Waves ◽  
Temperature Plasma ◽  
Ion Acoustic

scholarly journals Electron Beams and Langmuir Turbulence in Solar Type III Radio Bursts Observed in the Interplanetary Medium

1990 ◽  
Vol 142 ◽  
pp. 467-481
Author(s):  
R. P. Lin
Keyword(s):  
Interplanetary Medium ◽  
Electron Beams ◽  
Low Frequency ◽  
Langmuir Wave ◽  
Plasma Waves ◽  
Wave Number ◽  
Langmuir Waves ◽  
Decay Instability ◽  
Type Iii ◽  
Solar Type

The ISEE-3 spacecraft has provided in situ observations of electron beams, plasma waves, and associated solar type III radio emission in the interplanetary medium near 1 AU. These observations show that electron beams are formed by the faster electrons arriving before the slower ones, following an impulsive injection at the Sun. The resulting bump-on-tail in the reduced one-dimensional distribution function, f(v||), is unstable to the growth of electrostatic electron plasma (Langmuir) waves. The Langmuir waves are observed to be highly impulsive in nature. The onset and temporal variations of the observed plasma waves are in good qualitative agreement with the wave growth expected from the evolution of measured f(v||). However, far higher Langmuir wave intensities are predicted than are detected. In addition, the lack of obvious plateauing of the bump-on-tail suggests that the waves have been removed from resonance with the beam electrons by some wave-wave interaction. Bursts of low frequency, 30–300 Hz (in the spacecraft frame) waves are often found coincident in time with the most intense spikes of the Langmuir waves. These low-frequency waves appear to be long-wavelength ion acoustic waves, with wave number approximately equal to the beam-resonant Langmuir wave number. The observations suggest several possible interpretations: modulational instability, electrostatic decay instability, and electromagnetic decay instability; but none of these are fully consistent with the observations. Microstructures, too short in duration to be resolved by present experiments, have been invoked as an explanation of the phenomenon. Experiments are currently being developed to study these processes using fast wave-particle correlation techniques.

scholarly journals Generation of Low-Frequency Kinetic Waves at the Footpoints of Pre-Flare Coronal Loops

Solar Physics ◽  
2020 ◽  
Vol 295 (12) ◽  
Author(s):  
Alexandr Kryshtal ◽  
Anna Voitsekhovska ◽  
Oleg Cheremnykh ◽  
Istvan Ballai ◽  
Gary Verth ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Low Frequency ◽  
Small Scale ◽  
Plasma Parameters ◽  
Ion Acoustic Waves ◽  
Frequency Wave ◽  
Electric And Magnetic Fields ◽  
Ion Acoustic ◽  
Flare Process ◽  
Semi Empirical

AbstractIn this study we discuss the excitation of low-frequency plasma waves in the lower-middle chromosphere region of loop footpoints for the case when the plasma can be considered to be in a pre-flare state. It is shown that among the well-known semi-empirical models of the solar atmosphere, only the VAL (F) model together with a particular set of basic plasma parameters and amplitudes of the electric and magnetic fields supports generation of low-frequency wave instability. Our results show that it is possible to predict the onset of the flare process in the active region by using the interaction of kinetic Alfvén and kinetic ion-acoustic waves, which are solutions of the derived dispersion equation. The VAL (F) model allows situations when the main source of the aforementioned instability can be a sub-Dreicer electric field and drift plasma movements due to presence of spatial inhomogeneities. We also show that the generation of kinetic Alfvén and kinetic ion-acoustic waves can occur both, in plasma with a purely Coulomb conductivity and in the presence of small-scale Bernstein turbulence. The excitation of the small amplitude kinetic waves due to the development of low threshold instability in plasma with relatively low values of the magnetic field strength is also discussed.

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