Langmuir waves across the heliosphere

Briand, C.

doi:10.1017/s0022377815000112

Cited by 23 publications

(15 citation statements)

References 164 publications

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“…The properties of electron beams propagating in the heliosphere, in particular their density and velocity, depend on the electron acceleration mechanism, that can vary from electron accelerated during solar flares to electrons accelerated in front of shocks generated in the heliosphere (see a recent review paper on that aspect by Briand, ). The properties of the associated radio emission should reflect those of the electron beams.…”

Section: Discussionmentioning

confidence: 99%

Electromagnetic Simulations of Solar Radio Emissions

et al. 2019

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Solar radio emissions are electromagnetic waves emitted in the solar wind as a consequence of electron beams accelerated during solar flares or interplanetary shocks such as interplanetary coronal mass ejections. Different physical mechanisms have been suggested to describe their origin. A good understanding of the emission process would enable to infer the kinetic energy transferred from accelerated electrons to radio waves. Even if the electrostatic case has been extensively studied, full electromagnetic simulations were attempted only recently. In this work, we report large-scale 2D3V electromagnetic particle-in-cell simulations that enable to identify the generation of both electrostatic and electromagnetic waves originated by a succession of plasma instabilities. They confirm that an efficient mechanism to generate solar radio emissions close to T 2f , the harmonic of the plasma frequency, is a multistage model based on a succession of nonlinear three-wave interaction processes. Through a parametric study of the electron beam parameters, we show that (i) the global efficiency of the multistep conversion mechanism from the electron beam kinetic energy to the T 2f radio wave is independent of the beam parameters, approximately 10 −5 in all tested configurations, while (ii) the directivity of the electromagnetic radio wave strongly depends on the origin electron beam. Those results represent a step forward toward the use of solar wind radio emissions, observed remotely, as a diagnostic for the properties of the electron beam located at the source of the radio emission, and therefore to eventually better characterize remotely electron acceleration mechanisms in space regions not directly accessible to in situ measurements. Key Points:• We single out the successive steps of the generation mechanisms of solar radio emissions • We quantify the energy transferred from energetic particles to radio waves and show it is independent of energetic particles parameters • We identify the directivity of the radio emissions and show its strong dependence on energetic particles parameters.

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Section: Discussionmentioning

confidence: 99%

Electromagnetic Simulations of Solar Radio Emissions

et al. 2019

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“…We now Fourier transform with respect to T , so that ∂/∂T → −iW and spatial positions so that ∇ R → iK. The operators C and S can be expressed in terms of series containing W and K, best seen by (5).…”

Section: Perturbation Analysismentioning

confidence: 99%

“…The nonlinear evolution of high frequency electron plasma waves have been studied in great detail in part because these waves are often found in nature [1][2][3][4][5]. They are easily excited also in a laboratory.…”

Section: Introductionmentioning

confidence: 99%

Stability of electron wave spectra in weakly magnetized plasmas

Kono

Pécseli

2017

J. Plasma Phys.

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Analytical models for nonlinear electron plasma waves in weakly magnetized plasmas are developed for single as well as multi-mode conditions, with continuous wave spectra being a limiting case. The conditions for wave decay as well as modulational instabilities are analysed. Our results demonstrate that slow or nearly stationary plasma density variations can be found for weakly magnetized plasmas even for weakly nonlinear electron plasma waves without involving cavitation of large amplitude plasma waves. A reduction of the growth rates for decay as well as modulational instabilities are found when the spectral width of the wave spectrum is increased. Some of our results are relevant for the interpretation of the nonlinearly enhanced ion acoustic lines often observed in non-equilibrium ionospheres.

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“…Evidence for strong Langmuir turbulence (SLT; e.g. Robinson, 1997;Briand, 2015) has been found in anomalous radar echoes (Isham et al, 2012;Akbari et al, 2012) in the form of enhanced zero Doppler frequency features in the ion line spectra and enhanced backscatter at the plasma frequency.…”

Section: Introductionmentioning

confidence: 99%

Relation of anomalous F region radar echoes in the high-latitude ionosphere to auroral precipitation

Dahlgren¹,

Schlatter²,

Ivchenko³

et al. 2017

Ann. Geophys.

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Abstract. Non-thermal echoes in incoherent scatter radar observations are occasionally seen in the high-latitude ionosphere. Such anomalous echoes are a manifestation of plasma instabilities on spatial scales matching the radar wavelength. Here we investigate the occurrence of a class of spatially localized anomalous echoes with an enhanced zero Doppler frequency feature and their relation to auroral particle precipitation. The ionization profile of the E region is used to parametrize the precipitation, with nmE and hmE being the E region peak electron density and the altitude of the peak, respectively. We find the occurrence rate of the echoes to generally increase with nmE and decrease with hmE, thereby indicating a correlation between the echoes and high-energy flux precipitation of particles with a high characteristic energy. The highest occurrence rate of > 20 % is found for hmE = 109 km and nmE = 10 11.9 m −3 , averaged over the radar observation volume.

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Langmuir waves across the heliosphere

Cited by 23 publications

References 164 publications

Electromagnetic Simulations of Solar Radio Emissions

Electromagnetic Simulations of Solar Radio Emissions

Stability of electron wave spectra in weakly magnetized plasmas

Relation of anomalous F region radar echoes in the high-latitude ionosphere to auroral precipitation

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