Suprathermal Ion Acceleration at the Near-Sun Heliospheric Current Sheet Crossings observed by Parker Solar Probe During Encounters 7-15

We report observations of time-intensity profiles, velocity dispersion, pitch-angle distributions, spectral forms, and maximum energies of <500 keV/nucleon suprathermal (ST) H, He, O, and Fe ions in association with eight separate crossings of the heliospheric current sheet (HCS) that occurred near perhelia during Parker Solar Probe (PSP) encounters E7-E15. We find that the ST ion observations fall into three categories, namely: 1) the E07 observations posed serious challenges for existing models of ST ion production in the inner heliosphere; 2) ST observations during 6 separate HCS crossings are consistent with a scenario in which the accelerated ions escape out of sunward-located reconnection exhausts; and 3) a near 4-hr HCS crossing during E14 when PSP traversed regions close to the reconnection exhaust and observed ST protons up to ~550 keV in energy. The reconnection exhaust or the source of these ST ions subsequently moved outside of PSP orbit thus resulting in a >10:1 sunward flow of the accelerated ST ions. We present detailed analysis of the evolution of the pitch-angle distributions and spectral properties during this crossing which have revealed, for the first time, important clues about the nature of ion acceleration via reconnection-driven mechanisms at the near-Sun HCS.