Analysis of type III radio emissions observed by the Solar Orbiter spacecraft close to their source locations

<p>Type III radio emissions are often observed by the Solar Orbiter spacecraft in the solar wind. They arise from a mode conversion of Langmuir waves generated by electron beams ejected from the Sun. In this study, we analyze sources of type III radio emissions that occurred after July 2020. We use data from the Radio and plasma waves (RPW), Energetic particle detector (EPD), Magnetometer (MAG), and Solar Wind Analyzer (SWA) instruments. We identify in-situ type III events and examine various parameters that may have influenced their generation mechanism. We use the maximum amplitude (MAMP) data product from the Time Domain Sampler (TDS) receiver of the RPW instrument for continuous tracking of Langmuir wave packets. For in-situ type III events throughout the Solar Orbiter mission, we study the wave polarization of the locally generated Langmuir waves measured in the Y-Z plane of the spacecraft reference frame. Using data from the EPD instrument, we obtain electron beam velocities for several in-situ events. We show that the electron beam velocity for those events is higher than predicted by previous studies.</p>