An experimental Bullard-von Kármán dynamo

Mickaël Bourgoin (1) , Romain Volk (2) , Nicolas Plihon (2) , Pierre Augier (2) , Philippe Odier (2) , Jean-François Pinton (2)

1 LEGI - Laboratoire des Écoulements Géophysiques et Industriels [Grenoble]
2 Phys-ENS - Laboratoire de Physique de l'ENS Lyon

Inspired by a design originally proposed by Bullard ( 1955 Proc. Camb. Phil. Soc. 51 744), we report a simple experimental arrangement which generates a turbulent fluid dynamo in the laboratory. It is based on a von Karman gallium flow and it effectively models an 'alpha-omega' dynamo process, in which the alpha component is realized by external wirings, while the omega contribution fully incorporates the flow turbulence. In the dynamo state, we observe intermittent reversals of the dipole field, as well as excursions. The bifurcation develops through an 'on-off' regime.

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]; Mécanique des structures [physics.class-ph]

Mickaël Bourgoin, Romain Volk, Nicolas Plihon, Pierre Augier, Philippe Odier, et al.. An experimental Bullard-von Kármán dynamo. New Journal of Physics, 2006, 8, pp.329. ⟨10.1088/1367-2630/8/12/329⟩. ⟨hal-00492344⟩