Date of Award

Winter 2025

Project Type

Thesis

Program or Major

Electrical and Computer Engineering

Degree Name

Master of Science

First Advisor

Kent Chamberlin

Second Advisor

Matthew Argall

Third Advisor

Michael Carter

Abstract

This thesis describes the operation and error analysis for an instrument that is intended to measure current density in space, although there are other potential applications for the instrument. The device, named the Faraday Rotation Ammeter (FRA), utilizes the Faraday Rotation Effect to calculate current density, where the magnetic field created by a current density causes a shift in the polarization angle of light traveling in a fiber optic cable within the device. The fiber optic cable is wrapped into a ring structure oriented in a way so that the polarized source travels parallel to the magnetic field of interest, and the measured shift in polarization angle is used to infer the magnitude of the current density. An important feature of this device for space applications is that it can measure static as well as dynamic current densities, which is not a feature of sensors that are based on Faraday’s Law.

The contribution of this thesis is to further analyze the sensitivity of the FRA to determine the impact of each component on the accuracy of the device. The target accuracy and frequency band for the device is 100u A/m^2 over the range of DC to 4kHz. The original prototype for the FRA did not meet these requirements, which prompted the study reported here. The device performance was evaluated on a component-by-component basis for fiber optic cables and detector amplifiers to determine the major sources of error along with the component specifications that would be needed to achieve the desired performance. The results of this thesis showcase that measuring current densities in the range of uA/m^2 to A/m^2 is possible if lengths of fiber optic cable are able to be manufactured and birefringence induced by the fiber optic cable is reduced while less reliance can be placed on the polarimeter detector design than previously thought. The combined results of the sensitivity analysis will allow future efforts involving the FRA to be tested against these models to further validate not only this fiber optic current sensor design but also to investigate the measurement limits of the FRA for different applications.

Download

Share

COinS