Inhibition of type III radio emissions due to the interaction between two electron beams: Observations and simulations

Briand, C.; Henri, Pierre; Hoang, S.

doi:10.1002/2013ja019688

Cited by 9 publications

(9 citation statements)

References 24 publications

(26 reference statements)

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“…This type of cutoff has been reported earlier by Al-Hamadani, Pohjolainen, and Valtonen (2017). One possible explanation for the disappearance of type III radio emission could be a reduced level of beam-driven Langmuir waves, like when two electron beams cross and the radio emission becomes depleted (Briand, Henri, and Hoang, 2014). However, in this scenario the level of radio waves is recovered after the beam crossing, unlike in our event on 22 September 2011.…”

Section: Discussionsupporting

confidence: 83%

Visibility and Origin of Compact Interplanetary Radio Type IV Bursts

Sheshvan

Pohjolainen

2018

Sol Phys

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We have analyzed radio type IV bursts in the interplanetary (IP) space at decameter-hectometer (DH) wavelengths to determine their source origin and a reason for the observed directivity. We used radio dynamic spectra from the instruments on three different spacecraft, STEREO-A, Wind, and STEREO-B, which were located approximately 90 degrees apart from each other in 2011-2012, and thus gave a 360 degree view of the Sun. The radio data were compared to white-light and extreme ultraviolet (EUV) observations of flares, EUV waves, and coronal mass ejections (CMEs) in five solar events. We find that the reason that compact and intense DH type IV burst emission is observed from only one spacecraft at a time is the absorption of emission in one direction and that the emission is blocked by the solar disk and dense corona in the other direction. The geometry also makes it possible to observe metric type IV bursts in the low corona from a direction where the higher-located DH type IV emission is not detectable. In the absorbed direction we found streamers, and they were estimated to be the locations of type II bursts, caused by shocks at the CME flanks. The high-density plasma was therefore most probably formed by shockstreamer interaction. In some cases, the type II-emitting region was also capable of stopping later-accelerated electron beams, which were visible as type III bursts that ended near the type II burst lanes.

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Section: Discussionsupporting

confidence: 83%

Visibility and Origin of Compact Interplanetary Radio Type IV Bursts

Sheshvan

Pohjolainen

2018

Sol Phys

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“…Both processes (i) and (ii) are present in our numerical study, although we focus on the first one, based on the decay and coupling of waves, for which several proofs of occurrence in the interplanetary medium have been recently provided (Briand et al, ; Henri et al, , ).…”

Section: Introductionmentioning

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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“…Numerous observations from space instruments have provided in-situ measurements of these mechanisms in the very specific plasma environment of the interplanetary medium. Recently, relations between the frequencies, wavevectors and phases of the waves involved in the wave coupling mechanism have been confirmed [6,7]. However, these measurements remain limited spatially (single-point measurements of LWs) and temporally (due to the reduced telemetry).…”

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confidence: 99%

Laser-Plasma Interaction Experiment for Solar Burst Studies

et al. 2020

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A new experimental platform based on laser-plasma interaction is proposed to explore the fundamental processes of wave coupling at the origin of interplanetary radio emissions. It is applied to the study of electromagnetic (EM) emission at twice the plasma frequency (2ωp) observed during solar bursts and thought to result from the coalescence of two Langmuir waves (LWs). In the interplanetary medium, the first LW is excited by electron beams, while the second is generated by electrostatic decay of Langmuir waves. In the present experiment, instead of an electron beam, an energetic laser propagating through a plasma excites the primary LW, with characteristics close to those at near-Earth orbit. The EM radiation at 2ωp is observed at different angles. Its intensity, spectral evolution and polarization confirm the LW-coalescence scenario. PACS numbers:Solar flares generate intense electromagnetic (EM) radiations in the radio domain (1-100 MHz) that are the signature of electron beams propagating in the interplanetary medium [1,2]. Detected by space and ground-based radio telescopes, these EM waves could, in principle, provide characteristics of the electron beams, thus opening the prospect for direct applications in space weather. The individual steps resulting in such emission have been proposed in the 50's [3,4]: the fast electron beams generated during solar flares provide the free energy necessary to destabilize the interplanetary plasmas leading, in particular, to the excitation of electron plasma waves (Langmuir waves, LW) through beam-plasma instabilities. These can produce EM waves at the local plasma frequency (ω p ) or its harmonics. This paper focuses on the type-III radio bursts emitted at 2ω p , which is thought to come from a two-step mechanism:In step (1), known as the Langmuir Decay Instability (LDI), the primary LW decays into a secondary one (LW , almost counter-propagating) and an ion acoustic wave (IAW ). In step (2), known as Langmuir wave coalescence, the nonlinear coupling between the two LWs generates a current at 2ω p , a source term for an EM wave at the same frequency [4,5]. Numerous observations from space instruments have provided in-situ measurements of these mechanisms in the very specific plasma environment of the interplanetary medium. Recently, relations between the frequencies, wavevectors and phases of the waves involved in the wave coupling mechanism have been confirmed [6,7]. However, these measurements remain limited spatially (single-point measurements of LWs) and temporally (due to the reduced telemetry). Analytical models and numerical simulations have been developed to interpret these space observations. Recently, three-dimensional EM particle-in-cell simulations tackled several questions regarding the efficiency of the conversion process from LW to EM waves, and the emission pattern of the EM waves [8,9]. These models and simulations yet remain to be confronted with experimental data.Laboratory experiments provide a complementary and powerful method to study the fundament...

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Inhibition of type III radio emissions due to the interaction between two electron beams: Observations and simulations

Cited by 9 publications

References 24 publications

Visibility and Origin of Compact Interplanetary Radio Type IV Bursts

Visibility and Origin of Compact Interplanetary Radio Type IV Bursts

Electromagnetic Simulations of Solar Radio Emissions

Laser-Plasma Interaction Experiment for Solar Burst Studies

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