Mr. Zhiyu Yin
University of Maryland, College Park
A new method for the simulation of electron and ion acceleration during magnetic reconnection in macroscale systems
Magnetic reconnection drives the explosive release of magnetic energy in the heliosphere and the broader universe. The released energy drives high-speed flows, strong plasma heating and non-thermal distributions of energetic ions and electrons that can span many decades in energy. Modeling suggests that the production of non-thermal particles during magnetic reconnection is controlled by Fermi acceleration in macroscale magnetic fields and does not depend on kinetic-scale boundary layers. The new computational model, kglobal, is a blend of MHD and particle representations in which all kinetic scales are eliminated so that the model can be used to explore magnetic energy release in macrosystems. Here we report on kglobal simulations of reconnection-driven electron and ion acceleration. Electrons and ions form powerlaw distributions that extend nearly three decades in energy. An important result is that nonthermal ions typically gain greater energy than electrons, which has important consequences for understanding the energetics of flare energy release. The model is being tested by simulating a Parker Solar Probe (PSP) reconnection encounter in the heliospheric current sheet (HCS) that revealed strong ion energization with extended power law distributions. Using upstream parameters based on the data, we simulate the dynamics of reconnection in the HCS using kglobal and analyze the resulting spectra of energetic electrons and protons. The resulting proton spectra are in good agreement with the PSP observations. Thus, the direct simulation of non-thermal particle energization during reconnection in macrosystems is now possible.