Pressure–Strain Channels in Interchange Reconnection Simulation and Comparisons with MMS Observations

Abstract Pressure–strain interaction is an important channel for converting bulk-flow energy into heat in weakly collisionless plasmas. Its decomposition into compressive and incompressive work, how their relative importance depends on geometry, and how it relates spatially and statistically to electromagnetic work, remain unclear. Previous simulation studies of plasma turbulence and reconnection starting from weakly compressive initial data have typically found that incompressive work continues to dominate over compressive work. In contrast, many magnetospheric multiscale (MMS) mission events in the magnetosheath exhibit stronger compressive contributions. In this study, we investigate energy conversion in collisionless magnetic reconnection using fully kinetic particle-in-cell (PIC) simulations for interchange reconnection and compare the simulation results with MMS observations. The results show that electromagnetic work is highly localized near current layers, whereas pressure–strain work is distributed more broadly. The difference in their peak regions indicates a separation between where field-particle energy conversion occurs and where the bulk flow energy is converted into internal energy. These support a two-step energy conversion pathway for a Vlasov–Maxwell system and its dependence on reconnection geometries. The consistency between simulation and observation results underscores the pressure–strain diagnostics for understanding energy conversion in space plasmas.