New Results from the Three Meter Liquid Sodium Experiment with a Rough Inner Sphere

The origins of the Earth's magnetic field is an ongoing region of study, but is believed to arise from rotating, convecting, and electrically conducting fluid interactions in Earth's outer core. Using a series of experiments of increasing size and increasing power input (now a three-meter diameter system), we have examined liquid sodium spherical Couette flows to better understand the conditions that bring about Earth's dynamo. Turbulence, rotation, shear, zonal flows, turbulence, and the associated angular momentum fluxes are all naturally represented. Previous magnetic studies have recently uncovered magnetic field gain by the Omega effect while being sub-dynamo. After adding baffles to the inner sphere based on the advice of Finke and Tilgner 2014, we see greatly enhanced torques and induced magnetic fields. Our current experimental studies work to determine whether the strong induced magnetic fields are caused by interactions with the building/earth's magnetic field or a possible dynamo. In order to minimize the external magnetic field to better constrain the source of the induced magnetic fields, we have designed and implemented an initial canceling electromagnet with 1200 A-turns at the base of the experiment. We present initial experimental data and analysis with the canceling coil set up. We gratefully acknowledge the support of NSF EAR-1909055. The primary torque and magnetic field data presented here are from the dissertations of co-authors RR and AP.