Excitation of electron Langmuir frequency harmonics in the solar atmosphere

Фомичев, В. В.; Fainshtein, S. M.; Chernov, G. P.

doi:10.1134/s1063780x13050036

Cited by 4 publications

(3 citation statements)

References 12 publications

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“…Another modification of plasma emission, which is not discussed here, involves including a third harmonic (Takakura and Yousef, 1974;Zlotnik et al, 1998;Yoon et al, 2002;Fomichev et al, 2013).…”

Section: Fine Structuresmentioning

confidence: 99%

Coherent emission mechanisms in astrophysical plasmas

Melrose¹

2017

Rev. Mod. Plasma Phys.

187

123

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Three known examples of coherent emission in radio astronomical sources are reviewed: plasma emission, electron cyclotron maser emission (ECME) and pulsar radio emission.Plasma emission is a multi-stage mechanism with the first stage being generation of Langmuir waves through a streaming instability, and subsequent stages involving partial conversion of the Langmuir turbulence into escaping radiation at the fundamental (F) and second harmonic (H) of the plasma frequency. The early development and subsequent refinements of the theory, motivated by application to solar radio bursts, are reviewed. The driver of the instability is faster electrons outpacing slower electrons, resulting in a positive gradient (df (v )/dv > 0) at the front of the beam. Despite many successes of the theory, there is no widely accepted explanation for type I bursts and various radio continua.The earliest models for ECME were purely theoretical, and the theory was later adapted and applied to Jupiter (DAM), the Earth (AKR), solar spike bursts and flare stars. ECME strongly favors the x mode, whereas plasma emission favors the o mode. Two drivers for ECME are a ring feature (implying df (v)/dv > 0) and a loss-cone feature. Loss-cone driven ECME was initially favored for all applications. The now favored driver for AKR is the ring-feature in a horseshoe distribution, which results from acceleration by a parallel electric on converging magnetic field lines. The driver in DAM and solar and stellar applications is uncertain.The pulsar radio emission mechanism remains an enigma. Ingredients needed in discussing possible mechanisms are reviewed: general properties of pulsars, pulsar electrodynamics, the properties of pulsar plasma and wave dispersion in such plasma. Four specific emission mechanisms (curvature emission, linear acceleration emission, relativistic plasma emission and anomalous Doppler emission) are discussed and it is argued that all encounter difficulties.

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Section: Fine Structuresmentioning

confidence: 99%

Coherent emission mechanisms in astrophysical plasmas

Melrose¹

2017

Rev. Mod. Plasma Phys.

187

123

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“…The presence of bands at the third and higher plasma frequency harmonics in the dynamic spectra of type-II radio bursts requires an additional analysis of mechanisms for the generation of solar radio bursts. In [10], a mechanism for the generation of harmonics of the electron plasma frequency due to the development of explosive instability in plasma penetrated by an electron flow was considered; it was noted hat this mechanism might be responsible for the specific features of type-III radio bursts. In the present paper, we have analyzed the mechanism for the excitation of plasma frequency harmonics in type-II bursts.…”

Section: Discussionmentioning

confidence: 99%

“…One possible solution to this problem can be the development of explosive instability in the nonlinear interaction of three types of waves in the radiation source. In [10], a mechanism was considered according to which harmonics of the electron plasma frequency were generated as a result of the development of explosive instability in plasma penetrated by an electron flow. It was shown that this mechanism makes it possible to explain the emergence of higher harmonics with comparable intensities in the solar radio emission under the conditions existing in the sources of type-III radio burst.…”

Section: Introductionmentioning

confidence: 99%

On the Possibility of Generating Harmonics of the Electron Plasma Frequency in the Solar Atmosphere due to Explosive Instability in a System of Interpenetrating Electron and Ion Flows

2018

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An alternative mechanism is proposed for the generation of harmonics of the electron plasma frequency due to the development of explosive instability in a system of interpenetrating electron and proton flows in the solar atmosphere. The efficiency of the new mechanism in comparison with the earlier discussed mechanisms involving multistage processes of nonlinear interaction of waves in plasma is determined. It is shown that the development of explosive instability can lead to the excitation of the second and third harmonics of the plasma frequency with comparable amplitudes.

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Solar Radio Bursts Associated with Standing Shock Waves

Фомичев

Chernov

2020

Geomagn. Aeron.

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Excitation of electron Langmuir frequency harmonics in the solar atmosphere

Cited by 4 publications

References 12 publications

Coherent emission mechanisms in astrophysical plasmas

Coherent emission mechanisms in astrophysical plasmas

On the Possibility of Generating Harmonics of the Electron Plasma Frequency in the Solar Atmosphere due to Explosive Instability in a System of Interpenetrating Electron and Ion Flows

Solar Radio Bursts Associated with Standing Shock Waves

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