Date Thesis Awarded


Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)




George Vahala

Committee Members

Richard Marcus

Keith Griffioen


Superconducting Radio Frequency (SRF) cavities play a fundamental role in particle accelerators. Efficient operation depends on expelling magnetic flux from the cavity, and any residual flux that remains trapped after cooling below the critical temperature can have a significant impact on performance. Experimental evidence suggests that material defects as well as cooling protocols can have a strong impact on subsequent performance. To better understand these phenomena, we use time-dependent Ginzburg-Landau theory implemented as finite-element simulations. We adapt the theory to allow spatial variation of material-specific parameters along with realistic temperature dependencies. We report on numerical experiments for different configurations of defects such as pinning sites and grain boundaries, finding that grain boundaries have a much larger effect than pinning sites on the ability of a superconductor to expel magnetic flux. We also report on numerical experiments where we investigated effects of cooling speeds on magnetic flux expulsion, observing qualitative changes which occur when we change a parameter which controls the time dynamics of our simulations. We discuss implications for SRF cavity design and operation as well as future research.

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Creative Commons License
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