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We propose a plasma experiment to be used to investigate fundamental properties of astrophysical dynamos. The highly conducting, fast-flowing plasma will allow experimenters to explore systems with magnetic Reynolds numbers an order of…

Plasma Physics · Physics 2015-05-13 E. J. Spence , K. Reuter , C. B. Forest

Intense spin-down flows allow one to reach high Rm in relatively small laboratory setups using moderate mass of liquid metals. The spin-down flow in toroidal channels was the first flow configuration used for studying dynamo effects in…

Fluid Dynamics · Physics 2017-09-26 Peter Frick , Irina Mizeva

A non-linear, time-dependent, magnetically driven dynamo theory which shows how magnetically dominated configurations can relax to become helical on the largest scale available is presented. Coupled time-dependent differential equations for…

Astrophysics · Physics 2009-11-07 Eric G. Blackman , George B. Field

We consider the classical problem of kinematic dynamo action in simple steady flows. Due to the adjointness of the induction operator, we show that the growth rate of the dynamo will be exactly the same for two types of magnetic boundary…

Fluid Dynamics · Physics 2013-09-25 B. Favier , M. R. E. Proctor

The magnetic field measured in the Madison Dynamo Experiment shows intermittent periods of growth when an axial magnetic field is applied. The geometry of the intermittent field is consistent with the fastest growing magnetic eigenmode…

Plasma Physics · Physics 2009-11-11 M. D. Nornberg , E. J. Spence , R. D. Kendrick , C. M. Jacobson , C. B. Forest

We present an axisymmetric numerical model of a dynamo active accretion disc. If the dynamo-generated magnetic field in the disc is sufficiently strong (close to equipartition with thermal energy), a fast magneto-centrifugally driven…

Astrophysics · Physics 2009-10-31 Brigitta von Rekowski , Axel Brandenburg , Wolfgang Dobler , Anvar Shukurov

We numerically examine dynamo action generated by a flow of an electrically conducting fluid in a precessing cylindrical cavity. We compare a simplified kinematic approach based on the solution of the magnetic induction equation with a…

Fluid Dynamics · Physics 2025-04-07 André Giesecke , Mike Wilbert , Ján Šimkanin , Rainer Grauer , Frank Stefani

Arguments for and against the widely accepted picture of a solar dynamo being seated in the tachocline are reviewed and alternative ideas concerning dynamos operating in the bulk of the convection zone, or perhaps even in the near-surface…

Astrophysics · Physics 2007-05-23 Axel Brandenburg

To explain the large-scale magnetic field of the Sun and other bodies, mean-field dynamo theory is commonly applied where one solves the averaged equations for the mean magnetic field. However, the standard approach breaks down when the…

Solar and Stellar Astrophysics · Physics 2018-06-06 A. Brandenburg , P. Chatterjee

The paper deals with the integral equation approach to steady kinematic dynamo models in finite domains based on Biot-Savart's law. The role of the electric potential at the boundary is worked out explicitly. As an example, a modified…

Astrophysics · Physics 2009-05-20 Frank Stefani , Gunter Gerbeth , Karl-Heinz Rädler

Amplification of magnetic field due to kinematic turbulent dynamo action is studied in the regime of small magnetic Prandtl numbers. Such a regime is relevant for planets and stars interiors, as well as for liquid metal laboratory…

Solar and Stellar Astrophysics · Physics 2015-05-20 Leonid M. Malyshkin , Stanislav Boldyrev

Small scale turbulent dynamo action in compressible transonic turbulence is discussed. It is shown that the critical value of the magnetic Reynolds number displays a bimodal behavior and changes from a typical value of 35 for small Mach…

Astrophysics · Physics 2007-05-23 A. Brandenburg , N. E. L. Haugen , A. J. Mee

Dynamos wherein magnetic field is produced from velocity fluctuations are fundamental to our understanding of several astrophysical and/or laboratory phenomena. Though fluid helicity is known to play a key role in the onset of dynamo…

Plasma Physics · Physics 2023-07-05 Shishir Biswas , Rajaraman Ganesh

The meridional circulation plays an essential role in determining the basic mechanism of the dynamo action in case the of a low eddy diffusivity. Flux-transport dynamos with strong return flow and a deep stagnation point are discussed in…

Solar and Stellar Astrophysics · Physics 2015-06-03 Alfio Bonanno

Observations in polarized emission reveal the existence of large-scale coherent magnetic fields in a wide range of spiral galaxies. Radio-polarization data show that these fields are strongly inclined towards the radial direction, with…

Astrophysics · Physics 2009-11-13 Oliver Gressel , Udo Ziegler , Detlef Elstner , Günther Rüdiger

We present numerical investigations into three principal properties of the small-scale dynamo in stably stratified turbulence: the onset criterion, the growth rate, and the nature of the magnetic field anisotropy in the kinematic regime.…

Fluid Dynamics · Physics 2021-02-04 Valentin Skoutnev , Jonathan Squire , Amitava Bhattacharjee

We present numerical results on dynamo action in a flow driven by an azimuthal body force localized near the end of an elongated cylindrical container. The analysis focuses on the central region of the cylinder, where axial variations in…

Geophysics · Physics 2026-02-19 I. Grants , J. Priede

We present results from consistent dynamo simulations, where the electrically conducting and incompressible flow inside a cylinder vessel is forced by moving impellers numerically implemented by a penalization method. The numerical scheme…

Fluid Dynamics · Physics 2021-12-13 Sophia Kreuzahler , Yannick Ponty , Nicolas Plihon , Holger Homann , Rainer Grauer

Various aspects of the magnetism of the quiet sun are reviewed. The suggestion that a small scale dynamo acting at granular scales generates what we call the quiet sun fields is studied in some detail. Although dynamo action has been proved…

Solar and Stellar Astrophysics · Physics 2015-06-12 V. Martinez Pillet

The eigenvalues and eigenfunctions of a linear {\alpha}^{2}-dynamo have been computed for different spatial distributions of an isotropic \alpha-effect. Oscillatory solutions are obtained when \alpha exhibits a sign change in the radial…

Earth and Planetary Astrophysics · Physics 2012-08-08 A. Giesecke , F. Stefani , G. Gerbeth