scholarly journals Nonlinear finite-Larmor-radius effects in reduced fluid models

2008 ◽  
Vol 15 (8) ◽  
pp. 082302 ◽  
Author(s):  
A. J. Brizard ◽  
R. E. Denton ◽  
B. Rogers ◽  
W. Lotko
Keyword(s):  
Larmor Radius ◽  
Fluid Models ◽  
Finite Larmor Radius

scholarly journals Effects of finite Larmor radius on equilibria with flow in reduced two-fluid models

2008 ◽  
Author(s):  
Atsushi Ito ◽  
Noriyoshi Nakajima ◽  
Olivier Sauter ◽  
Xavier Garbet ◽  
Elio Sindoni
Keyword(s):  
Larmor Radius ◽  
Fluid Models ◽  
Finite Larmor Radius ◽  
Two Fluid

scholarly journals Finite Larmor radius regime: Collisional setting and fluid models

2019 ◽  
Vol 22 (06) ◽  
pp. 1950047
Author(s):  
Mihaï Bostan ◽  
Aurélie Finot
Keyword(s):  
Kinetic Energy ◽  
Subject Matter ◽  
Entropy Inequality ◽  
Collision Kernel ◽  
Larmor Radius ◽  
Fluid Models ◽  
Finite Larmor Radius ◽  
Collision Invariants ◽  
The Subject ◽  
Macroscopic Equations

The subject matter of this paper concerns the derivation of fluid limits for gyro-kinetic models. The arguments apply for any collision kernel satisfying the usual conservations (mass, momentum, kinetic energy) and possessing a production entropy sign. We describe the set of equilibria in terms of several moments, we determine the average collision invariants, and we write the associated macroscopic equations and the entropy inequality.

scholarly journals Electron-scale reduced fluid models with gyroviscous effects

2017 ◽  
Vol 83 (4) ◽  
Author(s):  
T. Passot ◽  
P. L. Sulem ◽  
E. Tassi
Keyword(s):  
Magnetic Energy ◽  
Pressure Fluctuations ◽  
Transverse Magnetic ◽  
Larmor Radius ◽  
Anisotropic Pressure ◽  
Turbulence Energy ◽  
Fluid Models ◽  
Magnetic Fluctuations ◽  
Pressure Balance ◽  
Finite Larmor Radius

Reduced fluid models for collisionless plasmas including electron inertia and finite Larmor radius corrections are derived for scales ranging from the ion to the electron gyroradii. Based either on pressure balance or on the incompressibility of the electron fluid, they respectively capture kinetic Alfvén waves (KAWs) or whistler waves (WWs), and can provide suitable tools for reconnection and turbulence studies. Both isothermal regimes and Landau fluid closures permitting anisotropic pressure fluctuations are considered. For small values of the electron beta parameter $\unicode[STIX]{x1D6FD}_{e}$, a perturbative computation of the gyroviscous force valid at scales comparable to the electron inertial length is performed at order $O(\unicode[STIX]{x1D6FD}_{e})$, which requires second-order contributions in a scale expansion. Comparisons with kinetic theory are performed in the linear regime. The spectrum of transverse magnetic fluctuations for strong and weak turbulence energy cascades is also phenomenologically predicted for both types of waves. In the case of moderate ion to electron temperature ratio, a new regime of KAW turbulence at scales smaller than the electron inertial length is obtained, where the magnetic energy spectrum decays like $k_{\bot }^{-13/3}$, thus faster than the $k_{\bot }^{-11/3}$ spectrum of WW turbulence.

Excitation of Alfvén waves by fast particles in a finite pressure plasma of adiabatic traps

1978 ◽  
Vol 20 (1) ◽  
pp. 137-148 ◽  
Author(s):  
B. I. Meerson ◽  
A. B. Mikhallovskii ◽  
O. A. Pokhotelov
Keyword(s):  
Uniform Magnetic Field ◽  
Alfven Waves ◽  
Larmor Radius ◽  
Alfvén Waves ◽  
Trapped Particles ◽  
Resonance Effects ◽  
Finite Larmor Radius ◽  
Pressure Plasma ◽  
Pressure Stabilization ◽  
Instability Growth

Resonant excitation of Alfvén waves by fast particles in a finite pressure plasma in a non-uniform magnetic field is studied. Plasma compressibility in the wave field is determined both by the curvature of the magnetic lines of force and finite Larmor radius of fast particles. A general expression for the instability growth rate is obtained and analyzed; the applicability of the results obtained in the previous paper has also been studied. The finite pressure stabilization of the trapped particles instability has been found. The bounce-resonance effects are analyzed.

scholarly journals Diffusion at the Earth magnetopause: enhancement by Kelvin-Helmholtz instability

2007 ◽  
Vol 25 (1) ◽  
pp. 271-282 ◽  
Author(s):  
R. Smets ◽  
G. Belmont ◽  
D. Delcourt ◽  
L. Rezeau
Keyword(s):  
Magnetic Field ◽  
Distribution Functions ◽  
Larmor Radius ◽  
Simple Analytical Model ◽  
Helmholtz Instability ◽  
Field Reversal ◽  
Finite Larmor Radius ◽  
The Earth ◽  
Specific Distribution ◽  
The Magnetic Field

Abstract. Using hybrid simulations, we examine how particles can diffuse across the Earth's magnetopause because of finite Larmor radius effects. We focus on tangential discontinuities and consider a reversal of the magnetic field that closely models the magnetopause under southward interplanetary magnetic field. When the Larmor radius is on the order of the field reversal thickness, we show that particles can cross the discontinuity. We also show that with a realistic initial shear flow, a Kelvin-Helmholtz instability develops that increases the efficiency of the crossing process. We investigate the distribution functions of the transmitted ions and demonstrate that they are structured according to a D-shape. It accordingly appears that magnetic reconnection at the magnetopause is not the only process that leads to such specific distribution functions. A simple analytical model that describes the built-up of these functions is proposed.

Finite-Larmor-radius stabilization of the m = 2 instability in the Isar T1-B high-beta stellarator

1977 ◽  
Vol 17 (1) ◽  
pp. 3-11 ◽  
Author(s):  
J. Neuhauser ◽  
M. Kaufmann ◽  
H. Röhr ◽  
G. Schramm
Keyword(s):  
Larmor Radius ◽  
Finite Larmor Radius ◽  
High Beta
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