Ion Acceleration at the Near-Sun Heliospheric Current Sheet Crossings observed by Parker Solar Probe During Encounters 7-22

We report observations of time-intensity profiles,pitch-angle distributions, spectral forms, and maximum energies of <500 keV/nucleon suprathermal (ST) H, He, O, and Fe ions in association with eleven separate crossings of the heliospheric current sheet (HCS) that occurred near perhelia during Parker Solar Probe (PSP) encounters E07-E21. 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 8 HCS crossings are consistent with a scenario in which the accelerated ions escape out of sunward-located reconnection exhausts; and 3) two HCS crossings (E14 & E20) when PSP traversed regions close to the reconnection exhaust and observed ST protons up to ~500 keV and >150 keV in energy. During the latter two crossings, PSP detected sunward-directed reconnection-generated plasma jets and sunward propagating energetic protons up to ~400 keV within the exhaust, thereby unambiguously establishing their origin from HCS-associated X-line located anti-sunward of PSP. 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.