Multi-fluid and kinetic models of partially ionized magnetic reconnection
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Harvard and Smithsonian, Cambridge, MA (United States)
Magnetic reconnection in partially ionized plasmas is a ubiquitous and important phenomenon in both laboratory and astrophysical systems. Here, simulations of partially ionized magnetic reconnection with well-matched initial conditions are performed using both multi-fluid and fully-kinetic approaches. Despite similar initial conditions, the time-dependent evolution differs between the two models. In multi-fluid models, the reconnection rate locally obeys either a decoupled Sweet–Parker scaling, where neutrals are unimportant, or a fully coupled Sweet–Parker scaling, where neutrals and ions are strongly coupled, depending on the resistivity. In contrast, kinetic models show a faster reconnection rate that is proportional to the fully-coupled, bulk Alfvén speed, $$v^*_A$$. In this work, these differences are interpreted as the result of operating in different collisional regimes. Multi-fluid simulations are found to maintain $$ν_{ni}L/v^*_A$$ ≳1, where $$ν_{ni}$$ is the neutral–ion collision frequency and L is the time-dependent current sheet half-length. This strongly couples neutrals to the reconnection outflow, while kinetic simulations evolve to allow $$ν_{ni}L/v^*_A$$ <1, decoupling neutrals from the reconnection outflow. Differences in the way reconnection is triggered may explain these discrepancies.
- Research Organization:
- Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Argonne National Laboratory (ANL), Argonne, IL (United States). Argonne Leadership Computing Facility (ALCF)
- Sponsoring Organization:
- National Aeronautics and Space Administration (NASA); National Science Foundation (NSF); USDOE Office of Science (SC)
- Grant/Contract Number:
- AC02-09CH11466; AC02-06CH11357
- OSTI ID:
- 1804609
- Alternate ID(s):
- OSTI ID: 1776994
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 4 Vol. 28; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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