Q-factor optimization for high-beta 650 MHz cavities for PIP-II
arXiv:2111.01894 · doi:10.1063/5.0068531
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.
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Cited by in corpus (3)
- Mid-T Heat Treatments on BCPed Coaxial Cavities at TRIUMF
- Nonequilibrium nonlinear response theory of amplitude-dependent dissipative conductivity in disordered superconductors
- Improved high-gradient performance for medium-velocity superconducting half-wave resonators: Surface preparation and trapped flux mitigation