The third harmonic of type III solar radio bursts

Takakura, T.; Yousef, Shahinaz

doi:10.1007/bf00151214

Cited by 44 publications

(14 citation statements)

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“…According to some reported observations (Reiner et al 1992;Zlotnik et al 1998), the 3H component is weaker than the 2H radiation. On the other hand, other observations report more intense 3H emission than the 2H component (Takakura & Yousef 1974). This conflicting relative difference in the radiation intensity has been the source of some controversy (Zlotnik 1978).…”

Section: Resultsmentioning

confidence: 99%

“…The radiation emission at higher harmonics of plasma frequency has been observed in solar and interplanetary environment (Kliem et al 1992;Zlotnik et al 1998;Takakura & Yousef 1974;Benz 1973;Cairns 1986). However, the issue of whether such a phenomenon is even possible in plasmas has not been resolved.…”

Section: Discussionmentioning

confidence: 99%

“…3H emissions have been reported in type II bursts (Kliem et al 1992;Zlotnik et al 1998) and type III bursts (Takakura & Yousef 1974;Benz 1973). Multiple harmonic emission up to fifth harmonic (5H) in the Earth's foreshock environment has been reported (Cairns 1986).…”

Section: Introductionmentioning

confidence: 99%

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Multiple harmonic plasma emission

Yoon

Ryu

2007

Physics of Plasmas

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Electromagnetic radiation at the plasma frequency and/or its second harmonic, the so-called plasma emission, is widely accepted as the fundamental process responsible for solar type II and III radio bursts. There have also been occasional observations of higher-harmonic plasma emissions in the solar-terrestrial environment. This paper presents the first demonstration of multiple harmonic emission by means of twodimensional electromagnetic particle-in-cell simulation. This finding indicates that under certain circumstances the traditional mechanism of fundamental-harmonic pair emission might also be accompanied by higher-harmonic components. Consequently, the present findings are highly relevant to in situ observations of third-and/or higher-harmonic plasma emission in astrophysical and solar-terrestrial environments.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Multiple harmonic plasma emission

Yoon

Ryu

2007

Physics of Plasmas

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“…The observations have also shown that the third harmonic emission is usually very weak. Here one should note that there are several observed cases of third harmonics in solar radio bursts [ Benz , ; Takakura and Yousef , ; Bakunin et al , ; Kliem et al ].…”

Section: Discussionmentioning

confidence: 99%

Observational evidence for the collapsing Langmuir wave packet in a solar type III radio burst

2013

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[1] High time resolution observations from the STEREO spacecraft show that in solar type III radio bursts, Langmuir waves often occur as very intense one-dimensional magnetic field aligned field structures. One of these events represents the most intense Langmuir wave packet with W L n e T e 7.2 10 -3 ever detected in a type III radio burst until now (W L is the peak energy density, and n e and T e are the electron density and temperature, respectively). The detailed analysis of this wave packet indicates that (1) its peak intensity is well above the threshold for the oscillating two-stream instability (OTSI) and supersonic collapse; (2) its peak intensity and spatial scale satisfy the criterion for it to be a collapsing envelope soliton; (3) its low-frequency components provide evidence for a density cavity, whose depth, width, and temporal coincidence indicate that probably it is the ponderomotive force generated density cavity; and (4) its spectrum contains harmonic peaks at 2f pe and 3f pe (in addition to the main Langmuir wave peak at the electron plasma frequency, f pe ), which, as indicated by the bispectral analysis, probably are of the electromagnetic waves generated as a result of coalescence of two oppositely propagating Langmuir waves, and a Langmuir wave and a second harmonic electromagnetic wave, respectively. These characteristics strongly suggest that this wave packet and its associated density cavity represent the collapsing envelope soliton-caviton pair formed as a result of OTSI, and in the present case, the strong turbulence processes probably play key roles in the beam stabilization as well as conversion of Langmuir waves into escaping radiation at 2f pe and 3f pe .

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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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The third harmonic of type III solar radio bursts

Cited by 44 publications

References 1 publication

Multiple harmonic plasma emission

Multiple harmonic plasma emission

Observational evidence for the collapsing Langmuir wave packet in a solar type III radio burst

Coherent emission mechanisms in astrophysical plasmas

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