Evidence of dual energy transfer driven by magnetic reconnection at sub-ion scales

The study of space plasmas at the kinetic scale has seen rapid growth in recent years due to the exponential increase in computational power and more accurate in-situ measurements. Both numerical simulations and observations have revealed a clear transition across ion scales from the magnetohydrodynamic (MHD) to the kinetic regime, characterized by different physical phenomena dominating the turbulent properties and the heating of plasmas. Several studies have associated the so-called ion break with magnetic reconnection, which is considered responsible for injecting energy into this range, thereby driving the sub-ion energy cascade.

In this work, we analyze a 2D3V hybrid-Vlasov simulation of forced plasma turbulence using the space-filtering (or coarse-graining) technique, which allows for a simultaneous investigation of energy transfer properties as a function of scale, space, and time. Using this approach, we quantitatively show, for the first time, that magnetic reconnection in non-collisional plasmas is associated with dual energy transfer across ion scales, bridging the MHD and kinetic regimes. The onset of reconnection events triggers the formation of sub-ion scale turbulent fluctuations and plays a crucial role in the appearance of an inverse energy transfer regime originating at these sub-ion scales.