LOFAR observations of Fine Fundamental and Harmonic Structures in Solar Radio Bursts by Xingyao Chen et al*1 May 2018, 10:01 UTC
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 those fine structures. It is widely believed that the small scale density inhomogeneities in the background plasma could create a clumpy distribution of Langmuir waves and generate the type IIIb fine structure (e.g., Takakura & Yousef 1975; Melrose 1983, Kontar 2001, Li et al 2012 and so on). We investigate the effects of background density fluctuations based on the striae structure observed with the Low Frequency Array (LOFAR) to estimate the density perturbation in the solar corona. The observations with high temporal (∼10 ms) and spectral (12.5 kHz) resolutions at 30–80 MHz allow us to observe these fine structures.
Figure 1. The top panel shows the dynamic spectrum of a clear type IIIb–type III burst pair in the frequency range of 30–80 MHz observed by LOFAR on 2015 April 16. ...