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We study an example of instability in presence of a multiplicative noise, namely the spontaneous generation of a magnetic field in a turbulent medium. This so-called turbulent dynamo problem remains challenging, experimentally and…

Astrophysics · Physics 2016-08-16 Nicolas Leprovost , Bérengère Dubrulle

The well known mean-field model of a turbulence driven dynamo is reviewed in relation to Laboratory experiments in which a turbulent cascade is created by a pair of large rotors. It is argued that in such experiments the alpha-effect,…

Fluid Dynamics · Physics 2012-10-16 J B Taylor

The magnetohydrodynamic dynamo equation is derived within general relativity, using the covariant 1+3 approach, for a plasma with finite electric conductivity. This formalism allows for a clear division and interpretation of plasma and…

Astrophysics · Physics 2009-11-10 Mattias Marklund , Chris Clarkson

A review of galactic magnetic fields is given with emphasis on simple analytical solutions of relevant equations and detailed comparison with observations. It is shown that mean-field dynamo theory, in its simplest form, is in a remarkably…

Astrophysics · Physics 2007-05-23 Anvar Shukurov

The purpose of this course is to provide an introduction to Electromagnetic Theory. The foundations of electrodynamics starting from the nature of electrical force up to the level of Maxwell equations solutions are presented. It starts with…

Accelerator Physics · Physics 2021-09-03 Irina Shreyber

The role of turbulence in various astrophysical settings is reviewed. Among the differences to laboratory and atmospheric turbulence we highlight the ubiquitous presence of magnetic fields that are generally produced and maintained by…

Solar and Stellar Astrophysics · Physics 2015-03-13 Axel Brandenburg , Aake Nordlund

In an experiment in the Institute of Continuous Media Mechanics in Perm (Russia) an non--stationary screw dynamo is intended to be realized with a helical flow of liquid sodium in a torus. The flow is necessarily turbulent, that is, may be…

Fluid Dynamics · Physics 2009-11-11 K. -H. Raedler , R. Stepanov

Magnetohydrodynamical (MHD) turbulence is ubiquitous in magnetized astrophysical plasmas, and it radically changes a great variety of astrophysical processes. In this review, we give the concept of MHD turbulence and explain the origin of…

Solar and Stellar Astrophysics · Physics 2023-02-24 Elena Popova , Alexandre Lazarian

The onset and evolution of magnetic fields in laboratory and astrophysical plasmas is determined by several mechanisms, including instabilities, dynamo effects and ultra-high energy particle flows through gas, plasma and interstellar-media.…

Plasma Physics · Physics 2015-05-20 A. Flacco , J. Vieira , A. Lifschitz , F. Sylla , S. Kahaly , M. Veltcheva , L. O. Silva , V. Malka

The version of electrodynamics is constructed in which faster-than-light motions of fields and particles with real masses are possible. Transformational properties of 3-velocity, momentum, energy and electromagnetic field are presented in…

Classical Physics · Physics 2007-05-23 Gennadii A. Kotel'nikov

Spiral galaxies, including the Milky Way, have large-scale magnetic fields with significant energy densities. The dominant theory attributes these magnetic fields to a large-scale dynamo. We review the current status of dynamo theory and…

Astrophysics of Galaxies · Physics 2023-08-31 Axel Brandenburg , Evangelia Ntormousi

We consider a semiconductor in a non-equilibrium steady state, with a dc current. On top of the stationary carrier motion there are fluctuations. It is shown that the stationary motion of the carriers (i.e., their drift) can have a profound…

Other Condensed Matter · Physics 2015-05-18 Boris Shapiro

In this paper, written as a general historical and technical introduction to the various review papers collected in the special issue ``Solar and Stellar Dynamo: A New Era'', we review the evolution and current state of dynamo theory and…

Solar and Stellar Astrophysics · Physics 2023-07-05 Paul Charbonneau , Dmitry Sokoloff

We review the basic ideas of the dynamical mean field theory (DMFT) and some of the insights into the electronic structure of strongly correlated electrons obtained by this method in the context of model Hamiltonians. We then discuss the…

Strongly Correlated Electrons · Physics 2007-05-23 G. Kotliar , S. Y. Savrasov

This pedagogical note revisits the concept of electromagnetic helicity in classical systems. In particular, magnetic helicity and its role in mean field dynamo theories is briefly discussed highlighting the major mathematical inconsistency…

High Energy Astrophysical Phenomena · Physics 2020-04-17 Amir Jafari

A combination of observation, theory, modeling, and laboratory plasma experiments provides a multifaceted approach to develop a much greater understanding of how magnetic fields arise in galactic settings and how these magnetic fields…

Astrophysics of Galaxies · Physics 2009-02-23 A. Lazarian , S. Boldyrev , C. Forest , J. Sarff , P. Terry

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

Numerical aspects of dynamos in periodic domains are discussed. Modifications of the solutions by numerically motivated alterations of the equations are being reviewed using the examples of magnetic hyperdiffusion and artificial diffusion…

Solar and Stellar Astrophysics · Physics 2011-06-14 Axel Brandenburg

The strong-field laser physics enterprise is investing important resources in the study of the effects of oscillatory electric fields on matter using the tunneling concept, whereas laser fields are vector fields that do not support the…

General Physics · Physics 2019-09-20 H. R. Reiss

When an electrically charged system is subjected to the action of an electromagnetic field, it responds by generating an electrical current. In the case of a multicomponent plasma other effects, the so called cross effects, influence the…

Astrophysics · Physics 2015-06-24 L. S. Garcia-Colin , A. L. Garcia-Perciante , A. Sandoval-Villalbazo