Date of Award

Spring 2001

Document Type

Restricted Thesis

Terms of Use

© 2001 Amy B. Reighard. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Physics & Astronomy Department

First Advisor

Michael R. Brown

Abstract

The conductivity of liquid sodium in a 0.15 m diameter spherical flask is measured directly using a precision current source and a nanovoltmeter, and indirectly using skin depth analysis. Direct resistance measurements are accurate to 1 μΩ. Averaging techniques help minimize the effects of DC offset, and contact voltage effects have been eliminated by using oxygen-free high conductivity copper for all metal contact points. Measurements of the conductivity are repeated at different fluid velocities, all at low magnetic Reynold's numbers (0 ≤ Rm ≤ 10), with the hypothesis that the conductivity of the sodium will decrease as the fluid velocity is increased. These measurements, when incorporated into mean-field electrodynamic dynamo theory, yield information about the β-coefficient of our system; β is a correction factor due to turbulence for the EMF in mean-field theory. Data from direct measurement reveals a small but positive β, effecting a decrease in the conductivity of sodium of a few percent. Data from the skin depth measurements confirm the trend of a decrease of conductivity at increasing magnetic Reynold's numbers. but are not statistically significant on their own.

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