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We explore the decay of turbulence and magnetic fields generated by fluctuation dynamo action in the context of galaxy clusters where such a decaying phase can occur in the aftermath of a major merger event. Using idealized numerical…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-28 Sharanya Sur

Magnetic field fluctuations in MHD turbulence can be viewed as current sheets that are progressively more anisotropic at smaller scales. As suggested by Loureiro & Boldyrev (2017) and Mallet et al (2017), below a certain critical thickness…

Plasma Physics · Physics 2017-08-09 Stanislav Boldyrev , Nuno F. Loureiro

We study the evolution of phase-transition-generated cosmic magnetic fields coupled to the primeval cosmic plasma in turbulent and viscous free-streaming regimes. The evolution laws for the magnetic energy density and correlation length,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Leonardo Campanelli

Observations have shown that the Sun's magnetic field has helical structures. The helicity content in magnetic field configurations is a crucial constraint on the dynamical evolution of the system. Since helicity is connected with the…

Solar and Stellar Astrophysics · Physics 2011-08-26 Simon Candelaresi , Fabio Del Sordo , Axel Brandenburg

The presence of large scale magnetic fields in nature is often attributed to the inverse cascade of magnetic helicity driven by turbulent helical dynamos. In this work we show that in turbulent helical dynamos, the inverse flux of magnetic…

Fluid Dynamics · Physics 2022-11-23 Guillaume Bermudez , Alexandros Alexakis

The dynamical motion of the magnetization plays a key role in the properties of magnetic materials. If the magnetization is initially away from the equilibrium direction in a magnetic nanoparticle, it will precess at a natural frequency…

Mesoscale and Nanoscale Physics · Physics 2015-06-23 M. G. Phelps , K. L. Livesey , A. M. Ferona , R. E. Camley

Combined action of helical motions of plasma (the $\alpha$ effect) and non-uniform (differential) rotation is a key dynamo mechanism of solar and galactic large-scale magnetic fields. Dynamics of magnetic helicity of small-scale fields is a…

Solar and Stellar Astrophysics · Physics 2022-09-20 N. Kleeorin , I. Rogachevskii

It is shown that in magnetohydrodynamics, the shapes of the magnetic energy and magnetic helicity spectra can influence whether the magnetic helicity resistive dissipation time scale is longer, equal to, or shorter than that of magnetic…

Astrophysics · Physics 2015-06-24 Eric G. Blackman

Relative magnetic helicity is a gauge invariant quantity suitable for the study of the magnetic helicity content of heliospheric plasmas. Relative magnetic helicity can be decomposed uniquely into two gauge invariant quantities, the…

Solar and Stellar Astrophysics · Physics 2018-10-10 Luis Linan , Étienne Pariat , Kostas Moraitis , Gherardo Valori , James E. Leake

We analyze the anisotropy of turbulence in an electrically conducting fluid in the presence of a uniform magnetic field, for low magnetic Reynolds number, using the quasi-static approximation. In the linear limit, the kinetic energy of…

Fluid Dynamics · Physics 2011-04-01 Benjamin F. N. Favier , Fabien S. Godeferd , Claude Cambon , Alexandre Delache

The emergence of a large scale magnetic field from randomly forced isotropic strongly helical flows is discussed in terms of the inverse cascade of magnetic helicity and the alpha-effect. In simulations of such flows the maximum field…

Astrophysics · Physics 2007-05-23 Axel Brandenburg

We provide a semiclassical theory of tunneling decay in a magnetic field and a three-dimensional potential of a general form. Because of broken time-reversal symmetry, the standard WKB technique has to be modified. The decay rate is found…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 T. Sharpee , M. I. Dykman , P. M. Platzman

The role of magnetic helicity in astrophysical large-scale dynamos is reviewed and compared with cases where there is no energy supply and an initial magnetic field can only decay. In both cases magnetic energy tends to get redistributed to…

Solar and Stellar Astrophysics · Physics 2009-11-13 Axel Brandenburg

We present a numerical and analytical study of incompressible homogeneous conducting fluids using a helical Fourier representation. We analytically study both small- and large-scale dynamo properties, as well as the inverse cascade of…

Fluid Dynamics · Physics 2017-03-02 Moritz Linkmann , Ganapati Sahoo , Mairi McKay , Arjun Berera , Luca Biferale

A three-dimensional numerical computation of magnetohydrodynamic dynamo behavior is described. The dynamo is mechanically forced with a driving term of the Taylor-Green type. The magnetic field development is followed from negligibly small…

Astrophysics · Physics 2007-05-23 P. D. Mininni , Y. Ponty , D. C. Montgomery , J. -F. Pinton , H. Politano , A. Pouquet

Previous work has introduced scale-split energy density \psi for a given vector field B in order to quantify the field stochasticity S(t). Application to turbulent magnetic fields leads to the prediction that tangling magnetic field by…

High Energy Astrophysical Phenomena · Physics 2020-02-26 Amir Jafari , Ethan Vishniac , Vignesh Vaikundaraman

We investigate tunneling decay in a magnetic field. Because of broken time-reversal symmetry, the standard WKB technique does not apply. The decay rate and the outcoming wave packet are found from the analysis of the set of the particle…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 T. Barabash-Sharpee , M. I. Dykman , P. M. Platzman

It is well known that non-ideal magnetohydrodynamic effects are important in the dynamics of molecular clouds: both ambipolar diffusion and possibly the Hall effect have been identified as significant. We present the results of a suite of…

Astrophysics of Galaxies · Physics 2014-11-20 T. P. Downes , S. O'Sullivan

Magnetohydrodynamic turbulence affects both terrestrial and astrophysical plasmas. The properties of magnetized turbulence must be better understood to more accurately characterize these systems. This work presents ideal MHD simulations of…

Fluid Dynamics · Physics 2021-04-28 Forrest W. Glines , Philipp Grete , Brian W. O'Shea

A gauge invariant and hence physically meaningful definition of magnetic helicity density for random fields is proposed, using the Gauss linking formula, as the density of correlated field line linkages. This definition is applied to the…

Astrophysics · Physics 2011-02-11 Kandaswamy Subramanian , Axel Brandenburg
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