Department of Physics Seminar Series

Optimizing Microstructure and Flux Management for High Q0 SRF Niobium Cavities

Dr. Pashupati Dhakal

Superconducting radio frequency (SRF) cavities are the building blocks of modern particle accelerators. Recent advances in impurity-diffusion surface treatments have enabled significant improvements in the quality factor (Q₀) of bulk niobium SRF cavities, offering pathways to reduce cryogenic operating costs in particle accelerators. While early high-Q₀ gains achieved through titanium and nitrogen doping were accompanied by reduced quench fields, lower-temperature heat treatments have shown promise in preserving accelerating gradients. A primary limitation to Q₀ arises from residual magnetic flux trapped during cavity cooldown, a sensitivity that increases with current high Q0 treatments.

In this presentation, I will update the recent studies on the role of microstructure on flux expulsion, flux pinning and its effect on high Q0 SRF cavities.