Topic
Antidynamo theorem
About: Antidynamo theorem is a research topic. Over the lifetime, 52 publications have been published within this topic receiving 1551 citations.
Papers published on a yearly basis
Papers
TL;DR: In this article, the dynamo equations describing the effects of the internal motion of a bounded volume of incompressible fluid with nonzero ohmic resistivity on the magnetic field produced by electric currents in that fluid were treated rigorously and a large class of continuously differentiable fluid velocities capable of indefinitely maintaining or amplifying the dipole moment of the external magnetic field was derived.
332 citations
TL;DR: In this article, the Ponomarenko dynamo is shown to be a fast dynamo and the maximum growth rate remains of order unity in the limit of large magnetic Reynolds number.
Abstract: An analysis of small-scale magnetic fields shows that the Ponomarenko dynamo is a fast dynamo; the maximum growth rate remains of order unity in the limit of large magnetic Reynolds number. Magnetic fields are regenerated by a “stretch-diffuse” mechanism. General smooth axisymmetric velocity fields are also analysed; these give slow dynamo action by the same mechanism.
97 citations
TL;DR: Measurements of the magnetohydrodynamic dynamo'' due to correlated fluctuations of velocity and magnetic field in the SPHEX spheromak show that there are both single-mode and turbulent dynamo processes present, although the single- mode process is in this case an antidynamo opposing the externally applied electric field.
Abstract: We present measurements of the magnetohydrodynamic ``dynamo'' due to correlated fluctuations of velocity and magnetic field in the SPHEX spheromak. We show that there are both single-mode and turbulent dynamo processes present, although the single-mode process is in this case an ``antidynamo'' opposing the externally applied electric field. The size of the turbulent dynamo at the magnetic axis is close to that required to drive the toroidal current there.
70 citations
TL;DR: In this article, the authors used numerical dynamo models to study the axisymmetrizing effects of stably stratified layers surrounding the dynamo, and they found that a thin stably-stratified layer which undergoes differential rotation due to thermal winds as a result of pole to equator temperature differences can produce a more axisymetrized field.
Abstract: [1] Magnetic field measurements demonstrate that Saturn's internally generated magnetic field has an extremely small dipole tilt. The nearly-perfect axisymmetry of Saturn's dipole is troubling because of Cowling's theorem which states that an axisymmetric magnetic field cannot be maintained by a dynamo. A possible mechanism to axisymmetrize the observed field involves differential rotation in a stably-stratified electrically conducting layer surrounding the dynamo. Here we use numerical dynamo models to study the axisymmetrizing effects of stably stratified layers surrounding the dynamo. We find that a thin stably-stratified layer which undergoes differential rotation due to thermal winds as a result of pole to equator temperature differences can produce a more axisymmetrized field. Surprisingly, we find that the direction of the zonal flows and their equatorial symmetry is a crucial factor for magnetic field axisymmetry since some zonal flows act to destabilize the dynamo producing non-axisymmetric fields.
57 citations
TL;DR: In this paper, the Cowling anti-dynamo theorem was proved using the Bullard and Gellman spectral formulation of kinematic dynamo theory, which is the basis for the present paper.
Abstract: The Cowling anti-dynamo theorem is proved using the Bullard and Gellman spectral formulation of kinematic dynamo theory.
18 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2017 | 1 |
| 2014 | 2 |
| 2012 | 1 |
| 2011 | 2 |
| 2010 | 5 |