Solar Type-IIIb Radio Bursts as Tracers for Electron Density Fluctuations in the Corona by V. Mugundhan et al.*17 Apr 2018, 09:31 UTC
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 of the beam propagation, there occur some fluctuations in the background electron density. These fluctuations give rise to “striations” seen as fine frequency structures in the dynamic spectrum (see Figure 1). Type III bursts, exhibiting such fine structures in frequency are called as Type IIIb bursts (de la Noe and Boischot, 1972). During observations using a high resolution spectrometer backend, around 20 such bursts were recorded during various days between July – October, 2016. Given the fact that density fluctuations create these striations, we sought to use these bursts to infer the properties of the former.
Figure 1. A Type IIIb burst, characterized by a drifting back-bone similar to a type III, but showing fine frequency structures, called striae.
The variation of the estimated values with heliocentric distance range was ...