Closure of the Strongly Magnetized Electron Fluid Equations in the Adiabatic Regime
نویسندگان
چکیده
We derive closure relations for a plasma fluid model, issued from the BGK equation for electrons in a strong magnetic-field. Our scaling of the BGK equation leads in the asymptotic limit ε → 0 towards the adiabatic electron regime, where ε embodies the scaled Larmor radius as well as a low Mach number. In this regime the electron density adjusts instantaneously to perturbations of the electric potential via a Boltzmann relation, i.e. n = ce . The fluid closures are obtained in the small-ε regime from a Hilbert ansatz of the distribution function; the ensuing hierarchy of kinetic equations is solved exactly up to the desired order. Different closures emerge depending on the importance of the ratio ν/ωc between the electron-electron collision frequency ν and the cyclotron frequency ωc. Anisotropy in the transport coefficients is found when ν/ωc 1. Moreover, bringing into play the obtained closures we present a drift-fluid model valid for ε 1, and identify the correct limit model as ε → 0. The limit model can be used to avoid the crude approximations c = const. and T = const. in the electron Boltzmann relation, frequently used for plasma simulations.
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ورودعنوان ژورنال:
- Multiscale Modeling & Simulation
دوره 14 شماره
صفحات -
تاریخ انتشار 2016