Constraints on the Formation and Structure of Langmuir Eigenmodes in the Solar Wind

Graham, Daniel B.; Cairns, Iver H.

doi:10.1103/physrevlett.111.121101

Cited by 16 publications

(44 citation statements)

References 33 publications

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“…One-dimensional (1-D) localized waveforms: Langmuir waves which are localized and have F < 0.2, as defined by equation (3). The waveform is single peaked and has an approximately Gaussian profile consistent with a zeroth-order (n = 0) Langmuir eigenmode solution of a density well Graham and Cairns, 2013b]. Generally, the electric field envelopes of localized wave packets have a small number of peaks, often a single peak.…”

Section: Event Classificationmentioning

confidence: 85%

“…The entire range of angles are observed from ∥ sw to ⟂ sw . The waveforms of 1-D packets are most commonly Gaussian, corresponding to the zeroth-order eigenmode solution of a single density well in one dimension Graham and Cairns, 2013b]. The peak in the histogram of all the events corresponds to ≈ 55 • .…”

Section: Dependence On the Angle Between The Magnetic Field And The Smentioning

confidence: 99%

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Dynamical evidence for nonlinear Langmuir wave processes in type III solar radio bursts

Graham

Cairns

2014

JGR Space Physics

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The nonlinear processes and evolution of Langmuir waves in the source regions of type III solar radio bursts are explored in detail. Langmuir waves recorded by the Time Domain Sampler of the STEREO/WAVES instrument can be roughly classified into six groups based on the waveform, power spectra, and field strength perpendicular to the local magnetic field. It is argued that these groups correspond to either different stages of the evolution of Langmuir waves generated by electron beams or differ due to the direction of the magnetic field relative to the solar wind velocity. Approximately half of the observed Langmuir waves have strong perpendicular fields, meaning that understanding how these fields are produced is crucial for understanding type III sources. Most events recorded are either localized waveforms consistent with Langmuir eigenmodes or have two or more spectral peaks consistent with electrostatic (ES) decay of Langmuir/z mode waves. The remaining events appear to correspond to either earlier or later stages of Langmuir wave evolution or are decay events for which the Doppler shift is insufficient to distinguish the beam‐driven and product Langmuir waves. This is supported by the fact that most events exceed the threshold for ES decay even though their spectra show no evidence for decay and some of the events are observed when the solar wind flow is approximately perpendicular to the magnetic field, minimizing Doppler shifting. Low‐frequency fields produced by intense Langmuir waves are quantitatively consistent with density perturbations produced by the ponderomotive force, ion‐acoustic waves produced by ES decay, or sheath rectification. Above the observed nonlinear threshold, quantitative analysis suggests that the observed low‐frequency signals are consistent with perturbations produced by ponderomotive effects and ion‐acoustic waves produced by ES decay, but effects of sheath rectification may also contribute.

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Section: Event Classificationmentioning

confidence: 85%

Section: Dependence On the Angle Between The Magnetic Field And The Smentioning

confidence: 99%

Dynamical evidence for nonlinear Langmuir wave processes in type III solar radio bursts

Graham

Cairns

2014

JGR Space Physics

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“…Waveforms of Langmuir eigenmodes in density cavities as observed and theoretically explained by Ergun et al (2008) and Graham and Cairns (2013b) were not a target of the simulations.…”

Section: Discussionmentioning

confidence: 99%

“…Among them are spectra with power at ω pe only (e.g., Sigsbee et al, 2010), a double peak in absence of ion acoustic activity (e.g., Sigsbee et al, 2010), multiple spectral peaks (e.g., Graham and Cairns, 2013a), a single peak with side-band structure (e.g., Gurnett at al., 1981;Thejappa et al, 2013), Langmuir eigenmodes localized in density wells (Ergun et al, 2008;Graham and Cairns, 2013b) and waveforms resulting from the interaction of Langmuir waves with electrostatic whistler/lower hybrid waves instead of ion sound (Stasiewicz et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

Ion dynamics in electron beam–plasma interaction: particle-in-cell simulations

Baumgärtel

2014

Ann. Geophys.

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Abstract. Electron beam-plasma interaction including ions is studied by particle-in-cell (PIC) simulations using a onedimensional, electrostatic code. Evidence for Langmuir wave decay is given for sufficiently energetic beams, as in previous Vlasov-Maxwell simulations. The mechanism for the generation of localized finite-amplitude ion density fluctuations is analyzed. Amplitude modulation due to interference between the beam-generated Langmuir waves causes random wave localization including strong transient spikes in field intensity which create bursty ion density structures via ponderomotive forces. More dense beams may quench the decay instability and generate low-frequency variations dominated by the wave number of the fastest growing Langmuir mode.

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“…4 Among them, interest in the collapse of Langmuir waves has grown due to its role in the understanding of the mechanism of energy transfer from the Langmuir waves to the background plasmas. 5,6 People have shown that the collapse of Langmuir waves, unlike the linear dissipation mechanisms, is accompanied by the development of a strong plasma turbulence and it has an amplitude threshold that depends on the distribution of the oscillations. 7,8 To describe the interaction between the high-frequency Langmuir waves and low-frequency ion-acoustic waves in the plasma, people have derived the Zakharov equations as follows: [9][10][11][12] …”

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confidence: 99%

Soliton solutions and chaotic motions of the Zakharov equations for the Langmuir wave in the plasma

et al. 2015

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For the interaction between the high-frequency Langmuir waves and low-frequency ion-acoustic waves in the plasma, the Zakharov equations are studied in this paper. Via the Hirota method, we obtain the soliton solutions, based on which the soliton propagation is presented. It is found that with λ increasing, the amplitude of u decreases, whereas that of v remains unchanged, where λ is the ion-acoustic speed, u is the slowly-varying envelope of the Langmuir wave, and v is the fluctuation of the equilibrium ion density. Both the head-on and bound-state interactions between the two solitons are displayed. We observe that with λ decreasing, the interaction period of u decreases, while that of v keeps unchanged. It is found that the Zakharov equations cannot admit any chaotic motions. With the external perturbations taken into consideration, the perturbed Zakharov equations are studied for us to see the associated chaotic motions. Both the weak and developed chaotic motions are investigated, and the difference between them roots in the relative magnitude of the nonlinearities and perturbations. The chaotic motions are weakened with λ increasing, or else, strengthened. Periodic motion appears when the nonlinear terms and external perturbations are balanced. With such a balance kept, one period increases with λ increasing.

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Constraints on the Formation and Structure of Langmuir Eigenmodes in the Solar Wind

Cited by 16 publications

References 33 publications

Dynamical evidence for nonlinear Langmuir wave processes in type III solar radio bursts

Dynamical evidence for nonlinear Langmuir wave processes in type III solar radio bursts

Ion dynamics in electron beam–plasma interaction: particle-in-cell simulations

Soliton solutions and chaotic motions of the Zakharov equations for the Langmuir wave in the plasma

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