Abstract:
Nowadays SRF cavities are mostly limited by material and surface science issues. Understanding the physical origin of defects and limitations helps to find or optimize effective cures and reduce the fabrication costs of this technology. After a brief presentation of Saclay activities, I will present the physical issues related to the use of bulk niobium, its surface and thermal treatments, then I will discuss briefly the superheating model vs early vortex penetration to predict the ultimate cavities performances, and explain why niobium achieves the best performances in RF. In a second part, I will present next generation superconductors: a new family of composite, nanostructured multilayers. I will present the challenges to be taken up from starting with model samples up to depositing deposing films into actual superconducting cavities. We will discuss advantage and drawback of various thin film deposition techniques, sample characterization developments and Saclay’s recent experimental results in that field..