Séminaire ISTerre

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Rough boundary spherical-Couette flows in the upgraded 3-m dynamo experiment

mardi 4 juillet 2023 - 11h15

Ruben Rojas Garcia - ETH Zurich
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The dynamo action is the process through which a magnetic field is amplified and sustained by electrically conductive flows. Galaxies, stars and planets, all exhibit magnetic field amplification by their conductive constituents. Throughout the last decades, spherical Couette experiments have been the preferred model to mimic some of these dynamics, giving insight into these natural phenomena. Almost all of them use liquid sodium between concentric spheres as the working fluid. In this present work we show results of the first rough boundary spherical Couette flow attempt to generate a dynamo in the lab. The roughness was reached by adding 6 asymmetric baffles with 5% of the inner sphere radius The experiment takes place at the University of Maryland and shows more than 2 times amplification of the fields compared with the smooth inner boundary case. However, torque limitations in the inner motor allowed us to inject only 4 times the available power. These results show the effect of the new baffles design in generating more efficient flows for magnetic field amplification and keep us optimistic about new short-term measurement in new locations of the parameter space. These setups constitute the first experimental explorations, in both hydrodynamics and magnetohydrodynamics, of rough boundary spherical Couette flows as laboratory candidates for successful Earth-like dynamo action.

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Equipe organisatrice : Géodynamo

Salle Dolomieu, Maison des Géosciences, 38400 Saint Martin d'Hères