Imaging Stray Magnetic Fields usind 3D Scanning Techniques

Lead Research Organisation: Cardiff University
Department Name: Sch of Engineering

Abstract

Mapping the magnetic field intensity at the surface provides information about a material's magnetic character as well as data relating to its physical state. This work will incorporate a state-of-the-art 3D scanning system to map out magnetic surface fields. The data will be used to construct detailed magnetic domain images on various types of as-cast amorphous ribbon. The work will involve developing LabVIEW software to operate the scanner and produce quantitative surface measurements and magnetic domain images. This will provide a useful technique for studying magnetic domain processes in magnetic materials.
 
Description PhD Thesis submitted 20th December 2019, PhD completed and awarded 30th July 2020

Summary
A new versatile magnetic field scanning system has been developed; based on a Micromagnetics® STJ-020 tunnelling magneto-resistance (TMR) sensor and a 3-axis positioning arm, with a 3D-printed sensor enclosure, precision goniometer and integrated microscopic sight. Calibration of the hardware, quantifying the slack/backlash of the three axes, and the capabilities of the system and its sensors are recounted. The system is capable of; scanning precisely and repeatably at 1 µm/step with a 4 x 2 µm2 sensing area; scanning smooth continuously dynamic magnetic field changes at a sampling frequency up to 1 MHz; producing scans of three-dimensional volumes; and resolving the "eld components along multiple axes. The Scanner Control so7ware (available as open access†) has been developed to be modular, powerful and adaptable, permitting large datasets from multiple sensors to be analysed. Studies are made of the domain structure in 3% Grain-Oriented Electrical Steel, Amorphous Alloy materials, Cubex doubly oriented Si-Fe Alloy and manufactured Planar coils, both statically and when reacting dynamically to externally applied alternating fields. Interpretation of the resulting field maps and comparison of the advantages and disadvantages of the Scanner system over other domain observation methods is given. The ability to scan a three-dimensional volume above the surface of the sample and to derive the Hz and Hx components from only a single axis sensor is developed and demonstrated, both statically and dynamically. The principles are tested against the known geometries of constructed planar coils, the expected fields from which are determined using Finite Element Modelling. The novel developments of the project, and the advantages of the developed Scanner System, culminate in, and are ultimately demonstrated by, the final dynamic three-dimensional, component-resolved stray-field scan of a volume above the surface of an unprepared sample of coated 3% grain-oriented electrical steel under alternating applied magnetic field.
Exploitation Route Others will read the thesis and use the system hardware and software that was developed for this PhD to pursue their own studies.
Sectors Electronics,Manufacturing, including Industrial Biotechology,Other
URL http://orca.cf.ac.uk/id/eprint/133528
 
Description Pursuing the PhD has trained me to tackle difficult problems from a self driven perspective and to pursue Research associate positions in numerous fields.
First Year Of Impact 2021
Sector Education,Electronics,Environment,Manufacturing, including Industrial Biotechology,Other
Impact Types Cultural,Societal