Spence E J, Nornberg M D, Jacobson C M, Parada C A, Taylor N Z, Kendrick R D, Forest C B
Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA.
Phys Rev Lett. 2007 Apr 20;98(16):164503. doi: 10.1103/PhysRevLett.98.164503. Epub 2007 Apr 19.
The nature of Ohm's law is examined in a turbulent flow of liquid sodium. A magnetic field is applied to the flowing sodium, and the resulting magnetic field is measured. The mean velocity field of the sodium is also measured in an identical-scale water model of the experiment. These two fields are used to determine the terms in Ohm's law, indicating the presence of currents driven by a turbulent electromotive force. These currents result in a diamagnetic effect, generating magnetic field in opposition to the dominant fields of the experiment. The magnitude of the fluctuation-driven magnetic field is comparable to that of the field induced by the sodium's mean flow.