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Related papers: Fluctuation Dynamo in Collisionless and Weakly Col…

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We study the linear stability of weakly magnetized differentially rotating plasmas in both collisionless kinetic theory and Braginskii's theory of collisional, magnetized plasmas. We focus on the very weakly magnetized limit that is…

Astrophysics of Galaxies · Physics 2015-06-23 Eliot Quataert , Tobias Heinemann , Anatoly Spitkovsky

In dilute astrophysical plasmas, the collisional mean free path of a particle can exceed its Larmor radius. Under these conditions, the thermal conductivity and viscosity of the plasma can be dramatically altered. This alteration allows…

Astrophysics · Physics 2009-11-11 Tanim Islam , Steven Balbus

The nonlinear state of a high-beta collisionless plasma is investigated when an imposed linear shear amplifies or diminishes a uniform magnetic field, driving pressure anisotropies and hence firehose/mirror instabilities. The evolution of…

High Energy Astrophysical Phenomena · Physics 2016-04-20 S. Melville , A. A. Schekochihin , M. W. Kunz

Weakly collisional plasmas dynamically develop pressure anisotropies with respect to the magnetic field. These anisotropies trigger plasma instabilities at scales just above the ion Larmor radius \rho_i and much below the mean free path…

High Energy Astrophysical Phenomena · Physics 2015-05-18 M. S. Rosin , A. A. Schekochihin , F. Rincon , S. C. Cowley

We show that under very general conditions, cluster plasmas threaded by weak magnetic fields are subject to very fast growing plasma instabilities driven by the anisotropy of the plasma pressure (viscous stress) with respect to the local…

Astrophysics · Physics 2008-11-26 A. A. Schekochihin , S. C. Cowley , R. M. Kulsrud , G. W. Hammett , P. Sharma

A concise review of observations of the $\alpha$ dynamo effect in laboratory plasmas is given. Unlike many astrophysical systems, the laboratory pinch plasmas are driven magnetically. When the system is overdriven, the resultant…

Astrophysics · Physics 2021-06-29 Hantao Ji , Stewart C. Prager

Hybrid-kinetic numerical simulations of firehose and mirror instabilities in a collisionless plasma are performed in which pressure anisotropy is driven as the magnetic field is changed by a persistent linear shear $S$. For a decreasing…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Matthew W. Kunz , Alexander A. Schekochihin , James M. Stone

Plasma in the terrestrial magnetosheath is characterised by very weak particle-particle collisions, so kinetic microinstabilities are thought to be responsible for regulating the thermodynamics of the plasma. By exciting electromagnetic…

Understanding magnetic-field generation and amplification in turbulent plasma is essential to account for observations of magnetic fields in the universe. A theoretical framework attributing the origin and sustainment of these fields to the…

Kinetic instabilities in weakly collisional, high beta plasmas are investigated using two-dimensional hybrid expanding box simulations with Coulomb collisions modeled through the Langevin equation (corresponding to the Fokker-Planck one).…

Plasma Physics · Physics 2019-02-20 Petr Hellinger , Pavel M. Travnicek

Using the magnetohydrodynamic (MHD) description, we develop a nonlinear dynamo model that couples the evolution of the large scale magnetic field with turbulent dynamics of the plasma at small scale by electromotive force (e.m.f.) in the…

Earth and Planetary Astrophysics · Physics 2011-09-29 Giuseppina Nigro , Pierlugi Veltri

Both global dynamics and turbulence in magnetized weakly collisional cosmic plasmas are described by general magnetofluid equations that contain pressure anisotropies and heat fluxes that must be calculated from microscopic plasma kinetic…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 A. A. Schekochihin , S. C. Cowley , F. Rincon , M. S. Rosin

When the ion mean free path much exceeds the Larmor radius in a plasma, the viscous stress tensor is altered dramatically, and depends only upon quantities measured along the field lines. This regime corresponds to typical interstellar…

Astrophysics · Physics 2009-11-10 Steven A. Balbus

Event horizon-scale observations of low-luminosity black hole accretion flows favor magnetically arrested disks, characterized by dynamically important magnetic fields ($\beta\lesssim1$, where $\beta$ is the ratio of plasma thermal pressure…

High Energy Astrophysical Phenomena · Physics 2026-03-10 Vedant Dhruv , Lorenzo Sironi , Jordy Davelaar , Aaron Tran

Upper bounds are derived on the amount of magnetic energy that can be generated by dynamo action in collisional and collisionless plasmas with and without external forcing. A hierarchy of mathematical descriptions is considered for the…

Plasma Physics · Physics 2017-01-11 P. Helander , M. Strumik , A. A. Schekochihin

In low-collisionality plasmas, anisotropic heat conduction due to a magnetic field leads to buoyancy instabilities for any nonzero temperature gradient. We study analogous instabilities in degenerate {\it collisional} plasmas, i.e., when…

High Energy Astrophysical Phenomena · Physics 2015-05-14 P Chang , E Quataert

Slow dynamical changes in magnetic-field strength and invariance of the particles' magnetic moments generate ubiquitous pressure anisotropies in weakly collisional, magnetized astrophysical plasmas. This renders them unstable to fast,…

Plasma Physics · Physics 2015-06-22 F. Rincon , A. A. Schekochihin , S. C. Cowley

Large-amplitude turbulence -- characterized by a fluctuating magnetic field component, $\delta B$, that is stronger than the mean component, $B_0$ -- is generically intermittent, populated with intense localized structures such as sharp…

High Energy Astrophysical Phenomena · Physics 2025-11-07 Ryan Golant , Luca Comisso , Philipp Kempski , Lorenzo Sironi

Among the fundamental and most challenging problems of laboratory, space, and astrophysical plasma physics is to understand the relaxation processes of nearly collisionless plasmas toward quasi-stationary states; and the resultant states of…

Space Physics · Physics 2022-01-12 C. M. Espinoza , P. S. Moya , M. Stepanova , J. A. Valdivia , R. E. Navarro

With the support of hybrid-kinetic simulations and analytic theory, we describe the nonlinear behaviour of long-wavelength non-propagating (NP) modes and fast magnetosonic waves in high-$\beta$ collisionless plasmas, with particular…

High Energy Astrophysical Phenomena · Physics 2023-04-05 Stephen Majeski , Matthew W. Kunz , Jonathan Squire