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TEA Lab Electromagnet

June 2021 - Feb. 2022

Context:

Summer of 2021, I joined the Transport for Energy Applications Lab (TEA Lab) at UCSB as a project intern. My assigned task was to work with another undergraduate student to create a uniform-field, 0.5 Tesla electromagnet to assist in Time-domain thermoreflectance (TDTR) measurements.

Preparation:

I did not have much experience with electromagnets and did not know how they worked well outside of simple wire-nail experiments I had done as a child. I started with researching how electromagnets worked, how they were made, and what their strength depended on. I also looked into current methods of how to create a uniform magnetic field. This included the possibilities of Helmholtz coils and circular cores with an air gap. 

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After my partner modeled the lab setup in SOLIDWORKS and we knew how much space we had to work with, we started on making a simple electromagnet to get familiar with the process of making one. We ordered a cast iron rod and graphed a portion of the hysteresis loop. 

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With the successful test of the cast iron core, we moved to a higher permeability metal, mild steel, and shaped it into our desired shape in the machine shop. 

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The core produced a slightly non-uniform magnetic field and went up to a magnetic field strength of 59.2 mT. Our original goal was to get up to 0.5 Tesla. To strengthen the field and make it more uniform, I contacted a professor, Prof. Doug Bradley, to make an iron core for us out of mild steel. I provided him with the sketch for the core along with the material and tolerances. We wrapped the new core in a lower gauge wire to increase current flow and decrease resistance which was causing the core to heat up quickly. 

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This mild steel core made by the professor was not as strong as the core my partner and I made ourselves. So we went back to the core we made and rewrapped it with the lower gauge, red wire. I wrapped as many loops as I could around the wire to increase the field strength according to the formula B = NLI or (magnetic field strength)=(loops per length)(length of core)(current through wires). 

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With this setup, we managed to reach a field strength of 104mT. While this was the highest field strength we had reached, the core was still heating up quite significantly and had a current of 4.3A. To increase the field strength more, we would need to simultaneously increase the amount of wire loops, increase the current through the wire, and find a way to cool the electromagnetic core. Our professor decided that he did not want to continue with the project stating, "No wonder the strong lab-grade electromagnets cost so much." 

Results and Lessons Learned:

We ended the project with a core that could produce 0.1 Tesla and maintain the field strength for a few minutes before overheating. While we didn't reach our goal of producing 0.5 Tesla, I still learned a lot about electromagnets and lab research. I gained experience with documenting my work, managing the experimental data, and plotting it in MATLAB. I also got introduced to COMSOL Multiphysics as I tried to model the electromagnets.

 

Below are some other things I learned while working on the project:

  • To start with any project, you have a goal in mind 

    • You know what you want and what you need out of the project to provide a final goal

  • Once you have the goal, move on to research. Look through research papers and other literature on the subject and related to the project

    • Look at what products already exist

    • Take notes, see what you can use, learn, and adapt

  • Brainstorm ideas and solutions

    • Think about what would achieve the goal the best, what would be easiest to make, what would be the quickest way, and what would be the least expensive

  • With any tests done or prototypes made, plan it out

    • Plan dimensions

    • Plan the process behind making the prototype or running the test

    • Plan what exactly you want to gain from a test

    • Plan how to do things efficiently and effectively

  • Use models as needed

  • Continue to adapt and adjust plans

  • Completing a project is good, but making sure you learn what you want from it is just as important

  • Build the habit of reading literature and papers

  • Some projects might need to be set aside or given up on depending on the benefits gained from the amount of effort required

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Overall, the professor seemed to like my work with the electromagnet and decided to keep me working in his lab on another project: Dynamics of Hydrogels. 

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