Center for Magnetic Self Organization

in Laboratory and Astrophysical Plasmas

Control of Turbulent Diffusion in a Liquid Metal Dynamo

Planetary, stellar, and probably galactic magnetic fields are sustained by dynamos, in which energy is transferred from the flows in the system usually rotation, convection, and turbulence to the magnetic field. But theory predicts that turbulence can also destroy the field. Destruction of a large scale field by small scale turbulence is known as the β effect. We have deployed small scale equatorial baffles in the liquid sodium Madison Dynamo Experiment. The baffles selectively damp the largest turbulent eddies. This results in reduced energy in the small scale magnetic field and increased energy in the large scale field, as predicted by dynamo theory.

Turbulence in the Madison Dynamo Experiment

Comparison of the power in magnetic modes in the Madison Dynamo Experiment without baffles (blue triangles) and with baffles (red squares). The dark red ovals show that the turbulent magnetic power is reduced by the baffles while the green ovals show that the power in the large scale field is enhanced without the baffles.

A National Science Foundation Physics Frontier Center,
established in coordination with the Department of Energy.