Open questions about homogeneous fluid dynamos: the VKS experiment

L. Marié¹ - F. Pétrélis² - M. Bourgoin³ - J. Burguete^1,4 - A. Chiffaudel¹ - F. Daviaud¹ - S. Fauve¹ - P. Odier² - J.-F. Pinton²

¹ Service de Physique de l'Etat Condensé, DSM/DRECAM, CEA/Saclay, 91191 Gif-sur-Yvette cedex, France
² Laboratoire de Physique Statistique de l'Ecole Normale Supérieure, CNRS UMR 8550, 24 Rue Lhomond, 75231 Paris cedex 05, France
³ Laboratoire de Physique de l'Ecole Normale Supérieure de Lyon, CNRS UMR 5672, 46 allée d'Italie, 69364 Lyon cedex 07, France
⁴ Present address: Departamento de Fisica y Matemática Aplicada, Universidad de Navarra E-31080 Pamplona, Spain

Abstract
We consider several problems that arise in the context of homogeneous fluid dynamos such as the effect of turbulence on the dynamo threshold, the saturation level of the generated magnetic field above the threshold and its dynamics. We compare some of our predictions with the recent experimental results of the Karlsruhe and Riga experiments. Finally, we present the VKS experiment that we have designed to answer some of the remaining open questions. We study, in particular, the response of a turbulent flow to an external magnetic field. Fig. 5, Refs. 42.