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Communication Dans Un Congrès Année : 2024

Titre : Kinetic effects in thin layers: effects on jump conditions and discontinuity properties

Résumé

In plasmas as in neutral fluids, there are a few types of well-established kinds of discontinuities: shocks, rotational discontinuities, etc., whose properties are based on the so-called "Rankine-Hugoniot" jump relations. In the classic theory, these relations are based only on universal conservation laws so that they are independent of the physics occurring inside the layer and of the theory used for describing it, fluid or kinetic. We will highlight what are the underlying assumptions behind the classic theory and show its limits. We will first make explicit the role of the pressure anisotropy, which is ubiquitous in magnetized plasmas. It makes in particular "evolutionary" the rotational discontinuity, so justifying its existence through wave steepening. Furthermore, we will show that the Finite Larmor radius (FLR) effects, implying non-gyrotropic pressure tensors, are of primary importance for the plasma equilibrium at thin layers, and that they can determine their stationary widths. Taking FLR effects into account results in discontinuity properties that are notably different from the classic ones in the quasi-tangential limit and can explain the observations at the terrestrial magnetopause. We show that the change concerning the rotational discontinuity is comparable to the change of the MHD Alfvén wave into a Kinetic Alfvén wave for the linear modes.
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Dates et versions

hal-04411744 , version 1 (23-01-2024)

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  • HAL Id : hal-04411744 , version 1

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G Belmont, G Ballerini, L Rezeau, F Califano. Titre : Kinetic effects in thin layers: effects on jump conditions and discontinuity properties. Vlasovia 2024, S. Landi, Jan 2024, Flocence, Italy. ⟨hal-04411744⟩
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