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arXiv · 2202.08541

Fokker-planck Multi-species Equations In The Adiabatic Asymptotics

Francis Filbet·Claudia Negulescu
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Abstract

The main concern of the present paper is the study of the multi-scale dynamics of thermonuclear fusion plasmas via a multi-species Fokker-Planck kinetic model. One of the goals is the generalization of the standard Fokker-Planck collision operator to a multispecies one, conserving mass, total momentum and energy, as well as satisfying Boltzmann's H-theorem. Secondly, the paper investigates in more details the reduced model used for the electron description in present simulations, and which considers the electrons in a thermodynamic equilibrium (adiabatic regime), whereas the ions are kept kinetic. On the one hand, we perform some mathematical asymptotic limits to obtain in the electron/ion low mass ratio limit the above-mentioned electron adiabatic regime. On the other hand, we develop a numerical scheme , based on a Hermite spectral method, and perfom numerical simulations to illustrate and investigate in more details this asymptotics.

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Francis Filbet, Claudia Negulescu. 2022-02-17. Fokker-planck Multi-species Equations In The Adiabatic Asymptotics. https://doi.org/10.1016/j.jcp.2022.111642

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