Generation of the Type III Radio Bursts: Comparison of the Model Results and Parker Solar Probe Observations

Parker Solar Probe (Parker) is capable of making observations of type III radio bursts in their generation region. PSP recorded a type III radio burst with frequency decay down to the local Langmuir frequency and simultaneously slow electrostatic plasma waves near the Langmuir frequency, which often harmonics. From the electric field fluctuations, the k-value of the Langmuir wave is estimated to be 0.14 and kλd = 0.4 and the phase velocity of the Langmuir wave was <10000km/s. The oscillations on the main frequency and the first harmonics were also detected in magnetic field perturbations. We demonstrated the presence of the second rapid Langmuir wave seen in the observations as the addition of two waves, one of which has small frequency variations that arise because the wave travels through density irregularities. This wave-wave interaction guided by a dense electron beam in the presence plasma density irregularities leads to the generation of the electromagnetic waves observed as type III radio burst