scholarly journals Vlasov simulation of Langmuir wave packets

2007 ◽  
Vol 14 (5) ◽  
pp. 671-679 ◽  
Author(s):  
T. Umeda
Keyword(s):  
Wave Packets ◽  
Langmuir Wave ◽  
Formation Processes ◽  
Ion Distribution ◽  
Langmuir Waves ◽  
One Dimensional ◽  
History Of ◽  
Turbulent Process ◽  
Weak Electron ◽  
Trapping Process

Abstract. Amplitude modulation and packet formation of Langmuir waves are commonly observed during a nonlinear interaction between electron beams and plasmas. In this paper, we briefly review the history of Langmuir wave packets as developed by recent spacecraft observations and computer simulations. New one-dimensional electrostatic Vlasov simulations are performed to study their formation processes. It is found that the formation of Langmuir wave packets involves both an incoherent turbulent process and a coherent nonlinear trapping process. Existence of cold ions does not affect nonlinear processes of the weak-electron-beam instability in which the ion distribution is hardly modified by the excited Langmuir wave packets.

Nonlinear Landau damping of large-amplitude Langmuir waves and formation of standing nonlinear waves

1980 ◽  
Vol 23 (3) ◽  
pp. 475-482 ◽  
Author(s):  
V. P. Pavlenko
Keyword(s):  
Thermal Plasma ◽  
Nonlinear Waves ◽  
Wave Packets ◽  
Langmuir Wave ◽  
Landau Damping ◽  
Characteristic Scale ◽  
Langmuir Waves ◽  
Slowing Down ◽  
Mechanism Of Interaction ◽  
Nonlinear Landau Damping

The interaction of nonlinear Langmuir wave packets corresponding to periodic solutions of the nonlinear Schrödinger equation with thermal plasma particles is considered. The mechanism of interaction is nonlinear Landau damping. The wave packets are slowed down owing to interaction but their amplitudes remain essentially unchanged. The characteristic scale lengths of the slowing down are determined.

scholarly journals Fundamental Electromagnetic Emissions by a Weak Electron Beam in Solar Wind Plasmas with Density Fluctuations

2022 ◽  
Vol 924 (2) ◽  
pp. L24
Author(s):  
C. Krafft ◽  
P. Savoini
Keyword(s):  
Electron Beam ◽  
Electromagnetic Radiation ◽  
Inhomogeneous Plasma ◽  
Langmuir Wave ◽  
Density Fluctuations ◽  
Electromagnetic Energy ◽  
Langmuir Waves ◽  
Harmonic Emission ◽  
Electromagnetic Emissions ◽  
Weak Electron

Abstract The generation of Langmuir wave turbulence by a weak electron beam in a randomly inhomogeneous plasma and its subsequent electromagnetic radiation are studied owing to two-dimensional particle-in-cell simulations in conditions relevant to type III solar radio bursts. The essential impact of random density fluctuations of average levels of a few percents of the background plasma on the characteristics of the electromagnetic radiation at the fundamental plasma frequency ω p is shown. Not only wave nonlinear interactions but also processes of Langmuir waves’ transformations on the density fluctuations contribute to the generation of such emissions. During the beam relaxation, the amount of electromagnetic energy radiated at ω p in a plasma with density fluctuations strongly exceeds that observed when the plasma is homogeneous. The fraction of Langmuir wave energy involved in the generation of electromagnetic emissions at ω p saturates around 10−4, i.e., one order of magnitude above that reached when the plasma is uniform. Moreover, whereas harmonic emission at 2ω p dominates over fundamental emission during the time evolution in a homogeneous plasma, fundamental emission is strongly dominant when the plasma contains density fluctuations, at least during several thousands of plasma periods before being overcome by harmonic emission when the total electromagnetic energy begins to saturate.

scholarly journals A linear model for amplitude modulation of Langmuir waves in weak electron-beam plasma interaction

2013 ◽  
Vol 31 (1) ◽  
pp. 31-38 ◽  
Author(s):  
K. Baumgärtel
Keyword(s):  
Amplitude Modulation ◽  
Langmuir Wave ◽  
Langmuir Waves ◽  
Plasma Interaction ◽  
Temporal Representation ◽  
Weak Beam ◽  
Beam Plasma ◽  
The Waves ◽  
Electron Beam Plasma ◽  
Weak Electron

Abstract. A simple linear approach to the phenomenon of amplitude modulation of Langmuir waves in weak beam plasma interaction is presented. During the short growth phase of the instability and within the longer period after saturation, the waves are described by their linear kinetic dispersion properties.The amplitude modulation appears as result of the beating of waves with different wavelengths and amplitudes that have grown from noise in the initial phase. The Langmuir wave fields are calculated via FFT (fast Fourier transform) technique. The resulting waveforms in temporal representation are quite similar to those observed by spacecraft.

scholarly journals Formation of quasi-power law weak Langmuir turbulence spectrum by harmonic generation

2004 ◽  
Vol 11 (2) ◽  
pp. 267-274
Author(s):  
P. H. Yoon
Keyword(s):  
Power Law ◽  
Langmuir Wave ◽  
Wave Number ◽  
Wave Turbulence ◽  
Langmuir Turbulence ◽  
Turbulence Spectrum ◽  
Langmuir Waves ◽  
Multi Scale ◽  
History Of ◽  
Simulation Results

Abstract. Langmuir wave turbulence generated by a beam-plasma interaction has been studied since the early days of plasma physics research. Despite a long history of investigation on this subject, among the outstanding issues is the generation of harmonic Langmuir waves observed in both laboratory and computer-simulated experiments. However, the phenomenon has not been adequately explained in terms of theory, nor has it been fully characterized by means of numerical simulations. In this paper, a theory of harmonic Langmuir wave generation is put forth and tested against the Vlasov simulation results. It is found that the harmonic Langmuir mode spectra exhibit quasi power-law feature implying a multi-scale structure in both frequency and wave number space spanning several orders of magnitude.

Statistical Analysis of Langmuir Waves Associated with Type III Radio Bursts: II. Simulation and Interpretation of the Wave Energy Distributions

2011 ◽  
Vol 20 (4) ◽  
Author(s):  
M. Maksimović ◽  
S. Vidojević ◽  
A. Zaslavsky
Keyword(s):  
Wave Energy ◽  
Probability Distributions ◽  
Wave Packets ◽  
Low Frequency ◽  
Langmuir Wave ◽  
Type I ◽  
Energy Distributions ◽  
Langmuir Waves ◽  
Pearson Type ◽  
Log Normal

AbstractWe have modeled electrostatic Langmuir waves by an electric field, consisting of superposition of Gaussian wave packets with several probability distributions of amplitudes and with several Poisson distributions of wave packets. The outcome of the model is that the WIND satellite observations, especially in the low frequency domain (the WAVES experiment), do not allow to conclude whether the input wave amplitude distributions are closer to the log-normal than to the Pearson type I or uniform. The average number of wave packets in 1 s is found to be between 0.1 and 50. Therefore, there is a clear need to measure Langmuir wave energy distributions directly at the waveform level, not a posteriori in the spectral domain. This is planned to be implemented on the RPW (Radio and Plasma Wave Analyzer) instrument in the Solar Orbiter mission.

scholarly journals Determining the wavelength of Langmuir wave packets at the Earth's bow shock

2011 ◽  
Vol 29 (3) ◽  
pp. 613-617 ◽  
Author(s):  
V. V. Krasnoselskikh ◽  
T. Dudok de Wit ◽  
S. D. Bale
Keyword(s):  
Wave Packets ◽  
Energetic Electron ◽  
Langmuir Wave ◽  
Field Measurements ◽  
Solar Wind Plasma ◽  
Density Fluctuations ◽  
Standard Theory ◽  
Langmuir Waves ◽  
High Frequency Electric Field ◽  
Earth’S Bow Shock

Abstract. The propagation of Langmuir waves in plasmas is known to be sensitive to density fluctuations. Such fluctuations may lead to the coexistence of wave pairs that have almost opposite wave-numbers in the vicinity of their reflection points. Using high frequency electric field measurements from the WIND satellite, we determine for the first time the wavelength of intense Langmuir wave packets that are generated upstream of the Earth's electron foreshock by energetic electron beams. Surprisingly, the wavelength is found to be 2 to 3 times larger than the value expected from standard theory. These values are consistent with the presence of strong inhomogeneities in the solar wind plasma rather than with the effect of weak beam instabilities.

scholarly journals How Should We Categorize Approaches to the History of Political Thought?

2020 ◽  
Vol 83 (1) ◽  
pp. 91-114
Author(s):  
Adrian Blau
Keyword(s):  
Theoretical Analysis ◽  
Political Theory ◽  
Political Thought ◽  
Two Dimensional ◽  
History Of Political Thought ◽  
One Dimensional ◽  
History Of ◽  
New Framework

AbstractThis paper proposes a new framework for categorizing approaches to the history of political thought. Previous categorizations exclude much research; political theory, if included, is often caricatured. And previous categorizations are one-dimensional, presenting different approaches as alternatives. My framework is two-dimensional, distinguishing six kinds of end (two empirical, four theoretical) and six kinds of means. Importantly, these choices are not alternatives: studies may have more than one end and typically use several means. Studies with different ends often use some of the same means. And all studies straddle the supposed empirical/theoretical “divide.” Quentin Skinner himself expertly combines empirical and theoretical analysis—yet the latter is often overlooked, not least because of Skinner's own methodological pronouncements. This highlights a curious disjuncture in methodological writings, between what they say we do, and what we should do. What we should do is much broader than existing categorizations imply.

scholarly journals On the semi-inverse method and variational principle

2013 ◽  
Vol 17 (5) ◽  
pp. 1565-1568 ◽  
Author(s):  
Xue-Wei Li ◽  
Ya Li ◽  
Ji-Huan He
Keyword(s):  
Heat Conduction ◽  
Variational Principle ◽  
Inverse Method ◽  
Generalized Variational Principle ◽  
Open Forum ◽  
One Dimensional ◽  
History Of

In this Open Forum, Liu et al. proved the equivalence between He-Lee 2009 variational principle and that by Tao and Chen (Tao, Z. L., Chen, G. H., Thermal Science, 17(2013), pp. 951-952) for one dimensional heat conduction. We confirm the correction of Liu et al.?s proof, and give a short remark on the history of the semi-inverse method for establishment of a generalized variational principle.

scholarly journals On the history of one-dimensional dynamics

2014 ◽  
Vol 46 ◽  
pp. 83-85
Author(s):  
A. N. Sharkovsky
Keyword(s):  
One Dimensional ◽  
History Of

scholarly journals Women and Gender in 1917

Slavic Review ◽  
2017 ◽  
Vol 76 (3) ◽  
pp. 694-702 ◽  
Author(s):  
Rochelle Goldberg Ruthchild
Keyword(s):  
Political Parties ◽  
Significant Issue ◽  
Women And Gender ◽  
One Dimensional ◽  
History Of ◽  
Key Issues ◽  
And Gender ◽  
Almost All ◽  
The Revolution

This paper argues for greater integration of considerations of women and gender in the history of the 1917 Russian Revolutions. Two key issues have long been discussed by historians: the spontaneity/consciousness paradigm, and the role of class in the revolution. Neither has been adequately analyzed in relation to gender. Women's suffrage has been largely neglected despite the fact that it was a significant issue throughout the year and represented a pioneering advance won by a countrywide coalition of women and men from the working class and intelligentsia, and from almost all political parties. In this centennial year, accounts of the Revolution remain one-dimensional; women remain the other.

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