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.
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.