Magnetoturbulence and Dynamos

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Background

Many celestial bodies—stars, planets, and in particular the Earth—produce magnetic fields in their interiors. Joseph Larmor first suggested in 1919 that the fields might arise via a feedback mechanism in the flow of conductive fluid in their cores, the so-called dynamo effect. Since then, the idea has come to be widely accepted among the astrophysics and geophysics communities but has not been definitively proven. Analytical “toy models” (such as those of Finn and Ott) have been studied extensively. Numerical simulations (such as those of Glatzmaier and Kuang) have produced dynamo action, but truly Earth-like parameters are too calculation-intensive to be accessible to simulation. Experimental dynamos have been found by teams in Riga, Latvia; Karlsruhe, Germany; and most recently in Cadarache, France. None have Earth-like geometry, however.

Our objectives

• Create a homogeneous, Earth-like dynamo in the lab.
• Demonstrate a self-generating magnetic field in an unconstrained flow.
• Characterize the nature of the transition to dynamo action.
• Explore the mechanism which causes Earth's magnetic field to saturate
• Understand the dynamics of the saturated field, with particular interest in pole reversals.

You can see our publications on the topics of magnetoturbulence and dynamo action.

Our experiments

Bigger is better when it comes to dynamo experiments. The larger the experiment, the larger the magnetic Reynolds number. The larger the magnetic Reynolds number, the better your chances are to self-generate magnetic fields.

Safety

These experiments use liquid sodium as the test fluid because of its high electrical conductivity. Sodium is chemically volatile, however, and using it safely requires caution, training, and specialized procedures. Oversight of our safety plan comes from two routes: the University of Maryland Environmental Health and Safety office, and the Engineering and Safety team at DuPont Sodium production facility. All of our safety plans and many refinements of those plans have been reviewed, and will be re-reviewed by these teams. Those recommendations will be strictly followed. Included in those plans are building modifications, personal protection equipment, and training. DuPont Corp. has given a day of training for both research personnel and the local fire department personnel on the safe handling and fire extinguishing practices for sodium. One pallet of drums of the soda ash fire fighting material will be on hand prior to receipt of the material. The safe conduct of our existing sodium experiments is some evidence of our ability to conduct these experiments, although the increased volume will require increased vigilance.

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