Evidence for nonlinear wave-wave interactions in solar type III radio bursts

Lin, R. P.; Levedahl, W. K.; Lotko, W.; Gurnett, D. A.; Scarf, F. L.

doi:10.1086/164563

Cited by 305 publications

(240 citation statements)

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“…As, we impose background magnetic field B 0x = 30 = const gauss along x-axis, plasma beta in this study, based on the above parameters, is set to β = 2(v th,i /c) 2 …”

Section: The Modelmentioning

confidence: 99%

An alternative to the plasma emission model: Particle-in-cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts

Tsiklauri

2011

Physics of Plasmas

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High-resolution (sub-Debye length grid size and 10000 particle species per cell), 1.5D Particle-inCell, relativistic, fully electromagnetic simulations are used to model electromagnetic wave emission generation in the context of solar type III radio bursts. The model studies generation of electromagnetic waves by a super-thermal, hot beam of electrons injected into a plasma thread that contains uniform longitudinal magnetic field and a parabolic density gradient. In effect, a single magnetic line connecting Sun to earth is considered, for which five cases are studied. (i) We find that the physical system without a beam is stable and only low amplitude level electromagnetic drift waves (noise) are excited. (ii) The beam injection direction is controlled by setting either longitudinal or oblique electron initial drift speed, i.e. by setting the beam pitch angle (the angle between the beam velocity vector and the direction of background magnetic field). In the case of zero pitch angle i.e. when v b · E ⊥ = 0, the beam excites only electrostatic, standing waves, oscillating at local plasma frequency, in the beam injection spatial location, and only low level electromagnetic drift wave noise is also generated. (iii) In the case of oblique beam pitch angles, i.e. when v b · E ⊥ = 0, again electrostatic waves with same properties are excited. However, now the beam also generates the electromagnetic waves with the properties commensurate to type III radio bursts. The latter is evidenced by the wavelet analysis of transverse electric field component, which shows that as the beam moves to the regions of lower density and hence lower plasma frequency, frequency of the electromagnetic waves drops accordingly. (iv) When the density gradient is removed, an electron beam with an oblique pitch angle still generates the electromagnetic radiation. However, in the latter case no frequency decrease is seen. (v) Since in most of the presented results the ratio of electron plasma and cyclotron frequencies is close to unity near the beam injection location, in order to prove that the generated by the non-zero pitch angle beam electromagnetic emission oscillates at the plasma frequency, we also consider a case when the magnetic field (and the cyclotron frequency) is ten times smaller. Within the limitations of the model, the study presents the first attempt to produce synthetic (simulated) dynamical spectrum of the type III radio bursts in the fully kinetic plasma model. The latter is based on 1.5D non-zero pitch angle (non-gyrotropic) electron beam, that is an alternative to the plasma emission classical mechanism for which two spatial dimensions are needed.

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“…As, we impose background magnetic field B 0x = 30 = const gauss along x-axis, plasma beta in this study, based on the above parameters, is set to β = 2(v th,i /c) 2 …”

Section: The Modelmentioning

confidence: 99%

An alternative to the plasma emission model: Particle-in-cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts

Tsiklauri

2011

Physics of Plasmas

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“…Astrophysical examples include Type II and III solar radio bursts (Lin et al 1981(Lin et al , 1986Dulk et al 1984;Goldman 1983;Robinson et al 1993aRobinson et al ,b, 1994Reid & Ratcliffe 2014), outer heliospheric radio emission (Kurth et al 1984), and in planetary electron foreshocks (Etcheto & Faucheux 1984;Moses et al 1984;Fuselier et al 1985;Lacombe et al 1985). Related processes in laboratory plasmas have also been discussed by, e.g.…”

Section: Introductionmentioning

confidence: 99%

Self-consistent particle-in-cell simulations of fundamental and harmonic plasma radio emission mechanisms

Thurgood

Tsiklauri

2015

A&A

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Aims. The simulation of three-wave interaction based plasma emission, thought to be the underlying mechanism for Type III solar radio bursts, is a challenging task requiring fully-kinetic, multi-dimensional models. This paper aims to resolve a contradiction in past attempts, whereby some studies indicate that no such processes occur. Methods. We self-consistently simulate three-wave based plasma emission through all stages by using 2D, fully kinetic, electromagnetic particle-in-cell simulations of relaxing electron beams using the EPOCH2D code.Results. Here we present the results of two simulations;, which we find to permit and prohibit plasma emission respectively. We show that the possibility of plasma emission is contingent upon the frequency of the initial electrostatic waves generated by the bump-in-tail instability, and that these waves may be prohibited from participating in the necessary three-wave interactions due to frequency conservation requirements. In resolving this apparent contradiction through a comprehensive analysis, in this paper we present the first self-consistent demonstration of fundamental and harmonic plasma emission from a single-beam system via fully kinetic numerical simulation. We caution against simulating astrophysical radio bursts using unrealistically dense beams (a common approach which reduces run time), as the resulting non-Langmuir characteristics of the initial wave modes significantly suppresses emission. Comparison of our results also indicates that, contrary to the suggestions of previous authors, an alternative plasma emission mechanism based on two counter-propagating beams is unnecessary in an astrophysical context. Finally, we also consider the action of the Weibel instability which generates an electromagnetic beam mode. As this provides a stronger contribution to electromagnetic energy than the emission, we stress that evidence of plasma emission in simulations must disentangle the two contributions and not simply interpret changes in total electromagnetic energy as evidence of plasma emission.

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“…According to the standard scenario, the streaming electrons excite Langmuir waves by the so-called bump-on-the-tail instability [Drummond and Pines, 1962;Vedenov et al, 1962], and part of the enhanced Langmuir waves may be converted to electromagnetic waves through nonlinear processes [e.g., Ginzburg and Zheleznyakov, 1958;Melrose, 1985]. In these discussions a positive slope of Earlier observations (e.g., by ISEE 3) [Lin et al, 1981[Lin et al, , 1986Lin, 1985] …”

Section: Introductionmentioning

confidence: 99%

Excitation of Langmuir waves in interplanetary space

Yoon¹,

Ziebell²,

Wu³

2000

J. Geophys. Res.

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Abstract. In this paper, the relation between the apparently stable or marginally stable electron reduced distribution and the excitation of Langmuir waves is discussed. It is found that the positive slope in the reduced distribution function is not always necessary for the excitation of Langmuir waves and that under certain circumstances, Langmuir waves propagating in oblique directions with respect to the ambient magnetic field can be excited by the electrons which may not have a bump in the reduced distribution.

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Evidence for nonlinear wave-wave interactions in solar type III radio bursts

Cited by 305 publications

References 0 publications

An alternative to the plasma emission model: Particle-in-cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts

An alternative to the plasma emission model: Particle-in-cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts

Self-consistent particle-in-cell simulations of fundamental and harmonic plasma radio emission mechanisms

Excitation of Langmuir waves in interplanetary space

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