Fundamental electromagnetic emissions by a weak electron beam in solar wind plasmas with density fluctuations by C. Krafft and P. Savoini

2022-04-05

Solar radio bursts of Type III were currently observed since decades in the interplanetary space (Reid and Ratcliffe, 2014). They result from a series of successive processes arising in solar coronal and wind plasmas where Langmuir wave turbulence is radiated by electron beams generated during flares, leading ultimately to the emission of electromagnetic waves at the fundamental plasma frequency $\omega _{p}$ and its second harmonic. The Letter by Krafft and […]

Characterising coronal turbulence using snapshot imaging of radio bursts in 80 – 200 MHz by Atul Mohan

2022-01-04

Metrewave solar type-III radio bursts offer a unique means to study the properties of turbulence across coronal heights. Theoretical models have shown that the apparent intensity and size of the burst sources evolve at sub-second scales due to turbulent scattering of radio waves close to their generation sites (Arzner & Magun, 1999; Kontar et al., 2019). The advent of high cadence snapshot spectroscopic imaging capabilities in meter wavebands have made […]

Langmuir wave motion observed in the most intense radio sources in the sky by H. Reid and E. Kontar

2021-08-31

The Sun routinely produces energetic electrons in its outer atmosphere that subsequently travel through interplanetary space. These electron beams generate Langmuir waves in the background plasma, producing type III radio bursts that are the brightest radio sources in the sky (Suzuki & Dulk, 1985). These solar radio bursts also provide a unique opportunity to understand particle acceleration and transport which is important for our prediction of extreme space weather events […]

Parametric simulation studies on the wave propagation of solar radio emission: the source size, duration, and position by Zhang et al.*

2021-05-11

The imaging and spectroscopy observations of solar radio bursts can provide information on the non-thermal electrons associated with the transient energy release in the solar active region and the parameters of the background plasma. However,  the corona plasma is an inhomogeneous refractive media for solar radio waves. Propagation effects, namely the refraction and scattering of waves, can cause the deformation of the observed radio source, including the expansion of the […]

Density Fluctuations in the Solar Wind Based on Type III Radio Bursts Observed by Parker Solar Probe by V. Krupar et al.*

2020-03-31

Type III bursts belong among the strongest radio signals routinely observed by both space-borne and ground-based instrumentations. They are generated via the plasma emission mechanism, when beams of suprathermal electrons interact with the ambient plasma triggering radio emissions at the plasma frequency (the fundamental emission) or at its second harmonic (the harmonic emission). As the electron beams propagate outward from the Sun, radio emissions are generated at progressively lower frequencies […]

Short-period Waves in Flare Loops: Possible Vehicle for Flare Energy Transport by Sijie Yu et al

2019-03-26

Solar flares involve the sudden release of magnetic energy in the solar corona. Accelerated nonthermal electrons have been often invoked as the primary means for transporting the bulk of the released energy to the lower solar atmosphere. However, significant challenges remain for this scenario, especially in accounting for the large number of accelerated electrons inferred from observations. Propagating magnetohydrodynamics (MHD) waves, particularly those with subsecond/second-scale periods, have been proposed as […]

LOFAR observations of Fine Fundamental and Harmonic Structures in Solar Radio Bursts by Xingyao Chen et al*

2018-05-01

Type III solar radio bursts are believed to be the most sensitive signatures of near-relativistic electron beam propagation in the corona. These intense bursts of solar radio emissions sometimes appear in the dynamic spectrum as a chain of several elementary bursts, which are known as striae, so an individual burst is composed of myriad of such stria (de La Noe & Boischot, 1972). Although there are several generation mechanisms of […]

Solar Type-IIIb Radio Bursts as Tracers for Electron Density Fluctuations in the Corona by V. Mugundhan et al.*

2018-04-17

Type III bursts are generated when an electron accelerated close to speed of light excite the layers of coronal plasma they encounter when travelling away from the sun. These bursts are seen in a time-frequency-intensity image (called dynamic spectrum, as the time variation of the spectrum is visualized by it) as a bright patch, drifting from high to low frequencies on short time-scales ($\approx$ few-seconds). At times, along the path […]

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