Characterization of experimental dynamos

Abstract

Laboratory models of geophysical magnetic field production require new experimental characterization methods. Self-generating liquid metal magnetic dynamos are explored using two new experiments. Kinematic dynamo studies lead us to characterize the magnetic field dynamics in terms of eigenvalues and eigenfrequencies of the induction equation. Observing the decay of magnetic field pulses indicates the real part of the leading eigenvalue of the induction equation, while a chirp magnetic field diagnoses the imaginary part of the eigenvalue. Finally, a single-frequency applied magnetic field characterizes the structure of the velocity field. These measurements provide a new means to characterize and measure the approach to self-generation. We present data from numerical simulations and laboratory experiments using these techniques.