Kinetic Features of Alpha Particles in a Pestchek-like Magnetic Reconnection Event in the Solar Wind Observed by Solar Orbiter

Abstract The acceleration and heating of solar wind particles by magnetic reconnection are important mechanisms in space physics. Although alpha ( 4 He 2+ ) the second most abundant population ions, their kinetic behavior is not well understood. Using high-energy (1500–3000 eV) range Solar Wind Analyser/Proton–Alpha Sensor instrument on board Orbiter, we study features an exhaust region a Pestchek-like solar-wind event with weak guide field. A pair back-to-back compound discontinuities observed region. We find that plasma heated bounded slow shocks (SSs), while accelerated jet rotational (RDs). SSs outside RDs, which expected from magnetohydrodynamical prediction. suggest this different location due to enhanced parallel temperature T p ∥ > ⊥ , reduces local Alfvén speed region, allowing propagate faster than RDs. Inside field dominant. two-population distribution particles. These two populations aligned downstream shift have perpendicular offset jet, suggesting change at RDs has similar timescales proton gyroperiod, but those particles, such behave like pickup ions.