Kinetic Imprints of Ion Acceleration in Collisionless Magnetic Reconnection

Fast collisionless magnetic reconnection implies fast energy conversion. The main form of energy conversion in magnetic reconnection concerns bulk ion acceleration with resulting ion jets. Based on theoretical analysis and MMS data, we examine the kinetic imprints of ion in the context of fast reconnection rates. The ion kinetic imprints we analyze in MMS observations include ion beams toward the X-line and distorted velocity distributions in reconnection jets. The distorted ion velocity distributions lead to a bipolar reversal in an off-diagonal element of the pressure tensor across the X-line, supporting an enhancement of the ion-scale reconnection electric field.