Decoding Ion Beams in the Solar Wind: Insights into Kinetic Processes and Acceleration Mechanisms

Ion beams are non Maxwellian features frequently observed in solar wind ion distribution functions. These beams appear as two distinct populations of ions with the same charge state but different bulk velocities. While various mechanisms – such as magnetic reconnection and resonant wave-particle interactions – have been proposed to explain their formation, their origin remains an open question and a subject of ongoing debate.

To better understand the kinetic processes driving particle acceleration, it is essential to identify and isolate the double streams in the particle measurements. To achieve this, we have developed a novel numerical method that leverages clustering techniques commonly used in machine learning. This approach enables the successful separation of up to four ion populations: the proton core and beam, as well as the alpha particle core and beam.

We present case studies in which proton and alpha beams were identified during specific events, such as magnetic switchbacks and interplanetary disturbances associated with solar eruptions. By isolating these beams, we examine their density, temperature, and velocity, and provide a detailed characterization of how the different distribution functions respond to such dynamic conditions.

These findings offer valuable insights into the intricate behavior of solar wind ions, shedding light on the underlying acceleration mechanisms and deepening our understanding of the complex processes shaping the solar wind.