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A two-scale hydromagnetic dynamo experiment

Published online by Cambridge University Press:  27 January 2004

U. MÜLLER
Affiliation:
Forschungszentrum Karlsruhe, Institut für Kern- und Energietechnik, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
R. STIEGLITZ
Affiliation:
Forschungszentrum Karlsruhe, Institut für Kern- und Energietechnik, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
S. HORANYI
Affiliation:
KFKI Atomic Energy Research Institute, Budapest, Hungary

Abstract

The Karlsruhe Dynamo experiment is aimed at showing that an array of columnar helical vortices in liquid sodium, confined in a cylindrical container, can generate a magnetic field by self-excitation. In three test series it has been demonstrated that magnetic self-excitation occurs and a permanent magnetic saturation field develops which oscillates about a well-defined mean value for fixed flow rates. Dynamo action is observed as an imperfect bifurcation from a seed magnetic field of the environment. Two quasi-dipolar magnetic fields of opposite direction have been realized. A transition between these two states can be enforced through imposition of a sufficiently strong external magnetic perturbation on the existent dynamo field. These perturbations were induced with the aid of two Helmholtz coils. A time series analysis of the magnetic field fluctuations shows several characteristic dynamic features, which are in agreement with theoretical predictions from turbulence models available in the literature.

Type
Papers
Copyright
© 2004 Cambridge University Press

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