Publication Date
2026
Document Type
Dissertation/Thesis
First Advisor
Fonseca, Benedito
Degree Name
M.S. (Master of Science)
Legacy Department
Department of Electrical Engineering
Abstract
Magnets are integral components of particle accelerators, with different multipoles used to perform various beam conditioning functions such as steering and focusing. Testing accelerator magnets to ensure compliance with specification is a crucial step of fabrication. One of the most popular techniques for verifying magnetic field strength and integrity is the harmonic coil probe. Harmonic coil probes are comprised of passive loops that are rotated around the aperture of a magnet, measuring magnetic flux. Oftentimes the measurements of harmonic coil probes are affected by transverse vibrations along the axis of rotation and torsional vibrations of the position closure sensor, both causing spurious harmonics. To make matters challenging, it is difficult to distinguish between the real harmonics of the magnet and the spurious harmonics during analysis.
This research explores the use of a novel configuration of harmonic coil probe, the Multi-Vertex Probe (MVP), to address multiple factors that affect the accuracy and repeatability of harmonic coil probe measurement. Most of the results are based on simulation data, in which artificial torsional distortions are introduced and removed with the proposed processing method. In addition to implementing torsional vibration removal in simulation, laboratory analysis regarding the sources of vibrations was performed using a prefabricated MVP. More specifically, various mechanical conditions were used to explore the standard deviation of main harmonic’s flux amplitude across vertices in the system. The conditions included: motor shaft coupling type, rotation speed, probe starting position within magnetic field, and cabling location inside the magnetic field. Along with this, the MVP’s measured noise floor in and outside a magnetic field was quantified.
Recommended Citation
Lofquist, Claire Mae, "Test of Harmonic Coil Accuracy Using a Multi Vertex Probe" (2026). Graduate Research Theses & Dissertations. 8221.
https://huskiecommons.lib.niu.edu/allgraduate-thesesdissertations/8221
Extent
167 pages
Language
en
Publisher
Northern Illinois University
Rights Statement
In Copyright
Rights Statement 2
NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.
Media Type
Text
