Proton Core, Proton Beam and Alpha Particle Kinetic Features Obtained from SWA-PAS 3D VDFs via an Innovative Code Based on Machine Learning

During the first quarter of 2022 Solar Orbiter experienced a large radial excursion between the Earth's orbit and its first close approach to the Sun at 0.32 AU. This orbital feature offers the possibility to study the radial evolution of the parameters characterizing the proton and the alpha particle populations in the solar wind. The separation of ion families in the measurements performed by electrostatic analyzers, however, is often a difficult task, due to the overlapping of the energy spectra. We adopted a novel numerical tool based on the machine learning technique of clustering which allows us to separate the proton core, the proton beam and the alpha particle populations directly form the 3D velocity distribution functions. Here, we focus on the kinetic features of the three ion families observed by SWA-PAS in Alfvénic intervals and we report on their statistical features and on their radial evolution with the heliocentric distance.