Generation of a magnetic field by dynamo action in a turbulent flow of liquid sodium.
We report the observation of dynamo action in the von Kármán sodium experiment, i.e., the generation of a magnetic field by a strongly turbulent swirling flow of liquid sodium. Both mean and fluctuating parts of the field are studied. The dynamo threshold corresponds to a magnetic Reynolds number R(m) approximately 30. A mean magnetic field of the order of 40 G is observed 30% above threshold at the flow lateral boundary. The rms fluctuations are larger than the corresponding mean value for two of the components. The scaling of the mean square magnetic field is compared to a prediction previously made for high Reynolds number flows.
Monchaux
R
R
Service de Physique de l'Etat Condensé, Direction des Sciences de la Matière, CEA-Saclay, CNRS URA 2464, 91191 Gif-sur-Yvette cedex, France.
Berhanu
M
M
Bourgoin
M
M
Moulin
M
M
Odier
Ph
P
Pinton
J-F
JF
Volk
R
R
Fauve
S
S
Mordant
N
N
Pétrélis
F
F
Chiffaudel
A
A
Daviaud
F
F
Dubrulle
B
B
Gasquet
C
C
Marié
L
L
Ravelet
F
F