Related papers: Optimization of the magnetic dynamo
Magnetostatic fields in accelerators are conventionally described in terms of multipoles. We show that in two dimensions, multipole fields do provide solutions of Maxwell's equations, and we consider the distributions of electric currents…
The magnetic field associated with neutron stars is generally believed to be threaded inside the star. In the presence of a magnetic field, the plasma present in the interior of the star goes through several processes that lead to magnetic…
We study the amplification of magnetic fields during the formation of primordial halos. The turbulence generated by gravitational infall motions during the formation of the first stars and galaxies can amplify magnetic fields very…
The axisymmetric 3-D MHD outflow of a cold plasma from a magnetized and rotating astrophysical object is numerically simulated with the purpose of investigating the outflow's magnetocentrifugal acceleration and eventual collimation. Gravity…
Glorified dimensional analysis is used to derive scaling rules for internal and external magnetic field strengths and various time scales. Naive dimensional analysis is inconclusive because of multiple time scales, but physical arguments…
Magnetic fields are considered to be key components of massive stars, with a far-reaching impact on their evolution and ultimate fate. A magnetic mechanism was suggested for the collimated explosion of massive stars, relevant for…
The galactic magnetic field is commonly supposed to be due to a dynamo acting on some large scale seed field. A major difficulty with this idea is that estimates of reasonable seed field strengths tend to be quite low, on the order of…
Magnetic fields have been detected on stars across the H-R diagram and substellar objects either directly by their effect on the formation of spectral lines, or through the activity phenomena they power which can be observed across a large…
Numerical simulations of outflows formed during the collapse of 100 M_sun cloud cores are presented. We derive a generalised criterion from MHD wind theory to analyse the launching mechanism of these outflows. The criterion is successfully…
Constraining dynamo theories of magnetic field origin by observation is indispensable but challenging, in part because the basic quantities measured by observers and predicted by modelers are different. We clarify these differences and…
We carry out an extended analytic study of how the tilt and faster-than-radial expansion from a magnetic field affect the mass flux and flow speed of a line-driven stellar wind. A key motivation is to reconcile results of numerical MHD…
The origin of cosmic magnetism is an issue of fundamental importance in astrophysics. We review here some of the ideas of how large scale magnetic fields in the universe, particularly in galaxies and galaxy clusters could arise. The popular…
The study of dynamo action in astrophysical objects classically involves two timescales: the slow diffusive one and the fast advective one. We investigate the possibility of field amplification on an intermediate timescale associated with…
One of the key questions in solar physics that remains to be answered concerns the strength and the distribution of the magnetic fields at the base of the convection zone. The flux tube dynamics requires that toroidal fields of strength as…
Kinematic dynamo in incompressible isotropic turbulent flows with high magnetic Prandtl number is considered. The approach interpreting an arbitrary magnetic field distribution as a superposition of localized perturbations (blobs) is…
Mean field dynamo theory is a leading candidate to explain the observed large scale magnetic fields of galaxies and stars. However, controversy arises over the extent of premature quenching by the backreaction of the growing field. We…
Scale separation between the flow and the magnetic field is a common feature of natural dynamos. It has also been used in the Karlsruhe sodium experiment in which the scale of the magnetic field is roughly 7 times larger than the scale of…
The kinematic dynamo problem is investigated for the flow of a conducting fluid in a cylindrical, periodic tube with conducting walls. The methods used are an eigenvalue analysis of the steady regime, and the three-dimensional solution of…
A magnetic field rotating on the free surface of a ferrofluid layer is shown to induce considerable fluid motion toward the direction the field is rolling. The measured flow velocity i) increases with the square of the magnetic field…
Models for the evolution of magnetic fields of neutron stars are constructed, assuming the field is embedded in the proton superconducting core of the star. The rate of expulsion of the magnetic flux out of the core, or equivalently the…