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The influence of fluctuating conductivity on the coefficients known from the mean-field electrodynamics is considered. If the conductivity fluctuations are assumed as uncorrelated with the turbulent velocity field then only the effective…

Plasma Physics · Physics 2020-07-15 G. Rüdiger , M. Küker , P. J. Käpylä

The current understanding of astrophysical magnetic fields is reviewed, focusing on their generation and maintenance by turbulence. In the astrophysical context this generation is usually explained by a self-excited dynamo, which involves…

Astrophysics · Physics 2008-11-26 Axel Brandenburg , Kandaswamy Subramanian

We consider the generation of magnetic field by the flow of a fluid for which the electrical conductivity is nonuniform. A new amplification mechanism is found which leads to dynamo action for flows much simpler than those considered so…

Fluid Dynamics · Physics 2016-05-04 Francois Petrelis , Alexandros Alexakis , Christophe Gissinger

The solar wind is a structured and complex system, in which the fields vary strongly over a wide range of spatial and temporal scales. As an example, the turbulent activity in the wind affects the evolution in the heliosphere of the…

Space Physics · Physics 2015-06-19 M. E. Ruiz , S. Dasso , W. H. Matthaeus , J. M. Weygand

The intermittency of density fluctuations in the solar wind at kinetic scales has been examined using high time resolution Faraday cup measurements from the Spektr-R spacecraft. It was found that the probability density functions (PDFs) of…

Space Physics · Physics 2014-06-23 C. H. K. Chen , L. Sorriso-Valvo , J. Šafránková , Z. Němeček

This letter presents the first ab initio, fully electromagnetic, kinetic simulations of magnetized turbulence in a homogeneous, weakly collisional plasma at the scale of the ion Larmor radius (ion gyroscale). Magnetic and electric-field…

Alfv\'en-wave turbulence has emerged as an important heating mechanism to accelerate the solar wind. The generation of this turbulent heating is dependent on the presence and subsequent interaction of counter-propagating alfv\'en waves.…

Solar and Stellar Astrophysics · Physics 2022-05-04 Chaitanya Prasad Sishtla , Jens Pomoell , Emilia Kilpua , Simon Good , Farhad Daei , Minna Palmroth

We investigate the intermittency of magnetic turbulence as measured in Reversed Field Pinch plasmas. We show that the Probability Distribution Functions of magnetic field differences are not scale invariant, that is the wings of these…

Plasma Physics · Physics 2007-05-23 V. Carbone , L. Sorriso-Valvo , E. Martines , V. Antoni , P. Veltri

Incompressible and isotropic magnetohydrodynamic turbulence in plasms can be described by an exact relation for the energy flux through the scales. This Yaglom-like scaling law has been recently observed in the solar wind above the solar…

Space Physics · Physics 2015-05-18 V. Carbone , R. Marino , L. Sorriso-Valvo , A. Noullez , R. Bruno

Many questions remain about the compressibility of solar wind turbulence with respect to its origins and properties. Low plasma beta (ratio of thermal to magnetic pressure) environments allow for the easier generation of compressible…

We investigate numerically magnetic field generation by thermal convection with square periodicity cells in a rotating horizontal layer of electrically-conducting fluid with stress-free electrically perfectly conducting boundaries for…

Chaotic Dynamics · Physics 2010-04-12 V. Zheligovsky

The generation and evolution of astrophysical magnetic fields occurs largely through the action of turbulence. In many situations, the magnetic field is strong enough to influence many important properties of turbulence itself. Numerical…

Astrophysics · Physics 2007-05-23 Ellen G. Zweibel , Fabian Heitsch , Yuhong Fan

Complete asymptotic expansions are developed for slow, Alfv\'en and fast magnetohydrodynamic waves at the base of an isothermal three-dimensional (3D) plane stratified atmosphere. Together with existing convergent Frobenius series solutions…

Solar and Stellar Astrophysics · Physics 2021-12-28 Paul S. Cally

Although it is widely accepted that photospheric motions provide the energy source and that the magnetic field must play a key role in the process, the detailed mechanisms responsible for heating the Sun's corona and accelerating the solar…

Solar and Stellar Astrophysics · Physics 2016-01-12 Roberto Lionello , Marco Velli , Cooper Downs , Jon A. Linker , Zoran Mikić

Recent observations indicate that kinetic and magnetic energies are not in equipartition in the solar wind turbulence. Rather, magnetic fluctuations are more energetic and have somewhat steeper energy spectrum compared to the velocity…

Astrophysics of Galaxies · Physics 2015-05-30 Stanislav Boldyrev , Jean Carlos Perez , Vladimir Zhdankin

Direct numerical simulations of two-dimensional decaying MHD turbulence in bounded domains show the rapid generation of angular momentum in nonaxisymmetric geometries. It is found that magnetic fluctuations enhance this mechanism. On a…

Plasma Physics · Physics 2010-09-02 Wouter J. T. Bos , Salah Neffaa , Kai Schneider

The strength and morphology of the Sun's magnetic field evolves significantly during the solar cycle, with the overall polarity of the Sun's magnetic field reversing during the maximum of solar activity. Long-term changes are also observed…

Solar and Stellar Astrophysics · Physics 2023-11-01 Adam J. Finley , Allan Sacha Brun

Magnetic switchbacks, large-amplitude, localized Alfvenic like rotations of the solar wind magnetic field, have been the subject of intensive investigation, with approximately 200 refereed papers published in the last decade. Yet,…

Solar and Stellar Astrophysics · Physics 2026-05-15 Forrest Mozer , Oleksiy Agapitov , Kyung-Eun Choi , Richard Sydora

Magnetic fluctuations generated by a tangling of the mean magnetic field by velocity fluctuations are studied in a developed turbulent convection with large magnetic Reynolds numbers. We show that the energy of magnetic fluctuations depends…

Astrophysics · Physics 2008-11-26 I. Rogachevskii , N. Kleeorin

Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. ULYSSES spacecraft solar polar passes at solar minimum provide \textit{in situ} observations of…

Plasma Physics · Physics 2015-05-14 S. C. Chapman , R. M. Nicol
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