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We study the effect of the non-linear process of ambipolar diffusion (joint transport of magnetic flux and charged particles relative to neutral particles) on the long-term behavior of a non-uniform magnetic field in a one-dimensional…

Solar and Stellar Astrophysics · Physics 2015-05-18 Jaime Hoyos , Andreas Reisenegger , Juan Valdivia

It is shown that ambipolar diffusion as a toy nonlinearity leads to very similar behaviour of large scale turbulent dynamos as full MHD. This is demonstrated using both direct simulations in a periodic box and a closure model for the…

Astrophysics · Physics 2007-05-23 Axel Brandenburg , Kandaswamy Subramanian

An analysis of instability dynamics in a stochastic magnetic field is presented for the tractable case of the resistive interchange. Externally prescribed static magnetic perturbations convert the eigenmode problem to a stochastic…

Plasma Physics · Physics 2023-06-14 Mingyun Cao , P. H. Diamond

We present EDDY (Exact-marginal Diversification via Divergence-free dYnamics), a guidance mechanism for diffusion and flow matching models that promotes diversity among samples generated while maintaining quality. EDDY exploits symmetries…

Machine Learning · Computer Science 2026-05-08 Gal Vinograd , Idan Achituve , Ethan Fetaya

We investigate the effects of a large-scale magnetic field with open field lines on the steady-state structure of a radiation-dominated accretion disk, using self-similarity technique. The disk is supposed to be turbulent and possesses an…

Astrophysics · Physics 2009-11-11 Mohsen Shadmehri , Fazeleh Khajenabi

Recent studies have demonstrated that in fully developed turbulence, the effective magnetic pressure of a large-scale field (non-turbulent plus turbulent contributions) can become negative. In the presence of strongly stratified turbulence,…

Solar and Stellar Astrophysics · Physics 2013-10-07 Axel Brandenburg , Nathan Kleeorin , Igor Rogachevskii

We investigate the stabilizing effects of the magnetic fields in the linearized magnetic Rayleigh-Taylor (RT) problem of a nonhomogeneous incompressible viscous magnetohydrodynamic fluid of zero resistivity in the presence of a uniform…

Mathematical Physics · Physics 2015-10-28 Fei Jiang , Song Jiang

Aims. We investigate the impact of ambipolar diffusion on the development of the Rayleigh-Taylor instability (RTI) with an oblique magnetic field in the incompressible limit. Methods. We developed a general bi-fluid framework comprising…

Astrophysics of Galaxies · Physics 2025-06-25 E. Callies , V. Guillet , A. Marcowith , Z. Meliani , P. Lesaffre

Temporal evolution of the inhomogeneous energy density driven instability (IEDDI) is examined in presence of a nonuniform transverse dc electric field in collisional magnetized plasma cylinder. Using experimentally known parameters relevant…

Plasma Physics · Physics 2007-05-23 Suresh C. Sharma , Satoshi Hamaguchi

We investigate the mean electromotive force in the kinematic framework, that is, ignoring the back-reaction of the magnetic field on the fluid velocity, under the assumption of axisymmetric turbulence determined by the presence of either…

Solar and Stellar Astrophysics · Physics 2012-02-23 A. Brandenburg , K. -H. Rädler , K. Kemel

We investigate electromagnetic buoyancy instabilities of the electron-ion plasma with the heat flux based on not the magnetohydrodynamic (MHD) equations, but using the multicomponent plasma approach when the momentum equations are solved…

Astrophysics of Galaxies · Physics 2015-05-27 Anatoly Nekrasov , Mohsen Shadmehri

We investigate the nonlinear instability of a smooth Rayleigh-Taylor steady-state solution (including the case of heavier density with increasing height) to the three-dimensional incompressible nonhomogeneous magnetohydrodynamic (MHD)…

Analysis of PDEs · Mathematics 2014-12-02 Fei Jiang , Song Jiang , Weiwei Wang

Strongly stratified hydromagnetic turbulence has previously been found to produce magnetic flux concentrations if the domain is large enough compared with the size of turbulent eddies. Mean-field simulations (MFS) using parameterizations of…

Solar and Stellar Astrophysics · Physics 2014-02-06 A. Brandenburg , O. Gressel , S. Jabbari , N. Kleeorin , I. Rogachevskii

We study magnetic field evolution in flows with fluctuating in time governing parameters in electrically conducting fluid. We use a standard mean-field approach to derive equations for large-scale magnetic field for the fluctuating ABC-flow…

Astrophysics · Physics 2009-11-13 N. Kleeorin , I. Rogachevskii , D. Sokoloff , D. Tomin

Global magnetohydrodynamic (MHD) instabilities are investigated in a computationally tractable two-dimensional model of the solar tachocline. The model's differential rotation yields stability in the absence of a magnetic field, but if a…

Plasma Physics · Physics 2019-02-19 Abigail Plummer , J. B. Marston , S. M. Tobias

A mean-field Fokker-Planck equation approach to the dynamics of ferrofluids in the presence of a magnetic field and velocity gradients is proposed that incorporates magnetic dipole-dipole interactions of the colloidal particles. The model…

Soft Condensed Matter · Physics 2015-06-24 Patrick Ilg , Siegfried Hess

We investigated a plasma system with kinematic viscosity ($\nu = 0.006$) and magnetic diffusivity ($\eta = 0.006$), driven by helical kinetic energy, to study the dynamics of energy and helicity in magnetic diffusion. Using the numerical…

Solar and Stellar Astrophysics · Physics 2024-12-20 Kiwan Park

Estimates for the nonlinear alpha effect in helical turbulence with an applied magnetic field are presented using two different approaches: the imposed-field method where the electromotive force owing to the applied field is used, and the…

Solar and Stellar Astrophysics · Physics 2009-11-13 A. Hubbard , F. Del Sordo , P. J. Käpylä , A. Brandenburg

We investigate the radial transport of magnetic flux in a thin accretion disc, the turbulence being modelled by effective diffusion coefficients (viscosity and resistivity). Both turbulent diffusion and advection by the accretion flow…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Jerome Guilet , Gordon I. Ogilvie

As was demonstrated in earlier studies, turbulence can result in a negative contribution to the effective mean magnetic pressure, which, in turn, can cause a large-scale instability. In this study, hydromagnetic mean-field modelling is…

Solar and Stellar Astrophysics · Physics 2012-02-21 K. Kemel , A. Brandenburg , N. Kleeorin , I. Rogachevskii