1. Q-factor optimization for high-beta 650 MHz cavities for PIP-II
- Author
-
Martinello, M., Bice, D. J., Boffo, C., Chandrasekeran, S. K., Eremeev, G. V., Furuta, F., Grassellino, A., Melnychuk, O., Sergatskov, D. A., Wu, G., and Reid, T. C.
- Subjects
Physics - Accelerator Physics ,Physics - Applied Physics - Abstract
High Q-factors are of utmost importance to minimize losses of superconducting radio-frequency cavities deployed in continuous wave particle accelerators. This study elucidates the surface treatment that can maximize the Q-factors in high-beta 650 MHz elliptical niobium cavities. State-of-the-art surface treatments are applied in many single-cell cavities, and surface resistance studies are performed to understand the microwave dissipation at this unexplored frequency. The nitrogen doping treatment is confirmed to be necessary to maximize the Q-factors at medium RF fields. We applied this treatment in five-cell high-beta 650 MHz cavities and demonstrated that extremely high Q-factors were obtained at medium RF fields with this treatment. We also demonstrated that adding a cold electropolishing step after N-doping is crucial to push the quench field of multicell cavities to higher gradients.
- Published
- 2021
- Full Text
- View/download PDF