Connecting Collisionless Landau Fluid Closures to Collisional Plasma Physics Models

Joseph, I.; Dimits, A. M.

doi:10.1002/ctpp.201610043

Cited by 10 publications

(7 citation statements)

References 25 publications

(52 reference statements)

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“…1993), later extended to include fourth-order moments (Hunana et al. 2018), and to include collisional effects without pitch-angle scattering (Joseph & Dimits 2016).…”

Section: Introductionmentioning

confidence: 99%

“…This restricts the application of standard fluid models to highly collisional regimes, therefore excluding Landau damping effects. In order to incorporate kinetic effects in fluid models, closures that mimic the linear response of a collisionless plasma have been derived (Hammett, Dorland & Perkins 1992;Hammett et al 1993), later extended to include fourth-order moments (Hunana et al 2018), and to include collisional effects without pitch-angle scattering (Joseph & Dimits 2016).…”

Section: Introductionmentioning

confidence: 99%

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Linear theory of electron-plasma waves at arbitrary collisionality

et al. 2019

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The dynamics of electron-plasma waves are described at arbitrary collisionality by considering the full Coulomb collision operator. The description is based on a Hermite-Laguerre decomposition of the velocity dependence of the electron distribution function. The damping rate, frequency, and eigenmode spectrum of electron-plasma waves are found as functions of the collision frequency and wavelength. A comparison is made between the collisionless Landau damping limit, the Lenard-Bernstein and Dougherty collision operators, and the electron-ion collision operator, finding large deviations in the damping rates and eigenmode spectra. A purely damped entropy mode, characteristic of a plasma where pitch-angle scattering effects are dominant with respect to collisionless effects, is shown to emerge numerically, and its dispersion relation is analytically derived. It is shown that such a mode is absent when simplified collision operators are used, and that like-particle collisions strongly influence the damping rate of the entropy mode. †

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“…1993), later extended to include fourth-order moments (Hunana et al. 2018), and to include collisional effects without pitch-angle scattering (Joseph & Dimits 2016).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Linear theory of electron-plasma waves at arbitrary collisionality

et al. 2019

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“…The moment method can be applied to the Landau fluid closures in Ref. [19] to obtain the exact linear response for arbitrary collisionality. In the Landau fluid models, the parallel moments are decomposed into parallel and perpendicular parts.…”

Section: Fitted Kernels For Integral Closuresmentioning

confidence: 99%

Ion parallel closures

Ji,

Lee,

Held

2019

Preprint

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Ion parallel closures are obtained for arbitrary atomic weights and charge numbers. For arbitrary collisionality, the heat flow and viscosity are expressed as kernel-weighted integrals of the temperature and flow-velocity gradients. Simple, fitted kernel functions are obtained from the 1600 parallel moment solution and the asymptotic behavior in the collisionless limit. The fitted kernel parameters are tabulated for various temperature ratios of ions to electrons. The closures can be used conveniently without solving the kinetic equation or higher order moment equations in closing ion fluid equations.

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“…We focus on collisionless closures and use a technique pioneered by Hammett & Perkins (1990). Alternative approaches, including incorporation of collisional effects, were presented for example by Joseph & Dimits (2016), Ji & Joseph (2018), Jorge et al (2019), Chen, Xu & Lei (2019), Wang et al (2019) and references therein.…”

Section: Introductionmentioning

confidence: 99%

An introductory guide to fluid models with anisotropic temperatures. Part 2. Kinetic theory, Padé approximants and Landau fluid closures

et al. 2019

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In Part 2 of our guide to collisionless fluid models, we concentrate on Landau fluid closures. These closures were pioneered by Hammett and Perkins and allow for the rigorous incorporation of collisionless Landau damping into a fluid framework. It is Landau damping that sharply separates traditional fluid models and collisionless kinetic theory, and is the main reason why the usual fluid models do not converge to the kinetic description, even in the long-wavelength low-frequency limit. We start with a brief introduction to kinetic theory, where we discuss in detail the plasma dispersion function Z(ζ), and the associated plasma response function R(ζ) = 1 + ζZ(ζ) = −Z ′ (ζ)/2. We then consider a 1D (electrostatic) geometry and make a significant effort to map all possible Landau fluid closures that can be constructed at the 4th-order moment level. These closures for parallel moments have general validity from the largest astrophysical scales down to the Debye length, and we verify their validity by considering examples of the (proton and electron) Landau damping of the ion-acoustic mode, and the electron Landau damping of the Langmuir mode. We proceed by considering 1D closures at higher-order moments than the 4th-order, and as was concluded in Part 1, this is not possible without Landau fluid closures. We show that it is possible to reproduce linear Landau damping in the fluid framework to any desired precision, thus showing the convergence of the fluid and collisionless kinetic descriptions. We then consider a 3D (electromagnetic) geometry in the gyrotropic (long-wavelength low-frequency) limit and map all closures that are available at the 4th-order moment level. In the Appendix A, we provide comprehensive tables with Padé approximants of R(ζ) up to the 8th-pole order, with many given in an analytic form.

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Connecting Collisionless Landau Fluid Closures to Collisional Plasma Physics Models

Cited by 10 publications

References 25 publications

Linear theory of electron-plasma waves at arbitrary collisionality

Linear theory of electron-plasma waves at arbitrary collisionality

Ion parallel closures

An introductory guide to fluid models with anisotropic temperatures. Part 2. Kinetic theory, Padé approximants and Landau fluid closures

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