Measurements and Simulations of the Madison Dynamo Experiment

Erik Spence (ETH Zurich)

The Madison Dynamo Experiment is designed to demonstrate magnetic
field self-excitation using flowing liquid sodium in a spherical
geometry. A turbulent flow is produced in the experiment by two
counter-rotating impellers. The role of turbulent velocity and
magnetic field fluctuations in magnetic field generation is explored
by applying an external magnetic field to the flowing sodium and
measuring the induced magnetic field. The experiment has not yet
fully self-excited, though it has demonstrated brief periods of rapid
magnetic field growth. The performance of the experiment is compared
to three-dimensional simulations of the experiment, which indicate
that as the fluctuation levels increase the ability of the system to
dynamo is comprised. By increasing the magnetic Reynolds number of
the simulations a turbulent dynamo re-emerges.