Conveners
M2Or3C - Focus Series C: Superconducting RF Cavity Materials I
- Lance Cooley (ASC/NHMFL - Florida State University)
- Pashupati Dhakal (SRF R&D Jefferson Lab)
Performance of superconducting radio-frequency (SRF) cavities is determined by the property of the material within the first hundred of micrometers from the surface. A general overview of the state-of-the-art surface treatments for SRF application will be presented, highlighting how each treatment change the surface properties, and how that affects the RF surface resistance. Recent R&D...
Niobium used in Nb3Sn multifilamentary superconductor wire and superconducting radio frequency cavities is initially cast and then receives a series of deformation and annealing steps to bring it to final component dimensions. The intermediate and final annealing steps are applied in order to recrystallize and soften the microstructure for subsequent shaping or additional mechanical...
Niobium provides the basis for all superconducting radio frequency cavities in use. However, flux pinning at lattice imperfections significantly contributes to degradation in niobium performance at high radio frequency accelerating fields. Lattice defects, such as dislocations and grain boundaries, pin the field inside the material even after the external magnetic field is removed thereby...
High purity Niobium possesses superconducting properties that make it a particularly suitable material for superconducting radio frequency (SRF) cavities. Most SRF cavities are made from rolled Nb sheet material, by deep drawing dishes, cutting a central hole, and joining the dishes with seam welds. Fabrication of seamless Nb tubes by hydroforming could lead to improved economics for seamless...
Nitrogen doping and heat treatment procedures have boosted the performance of SRF cavities by reaching higher quality factors (Q ~5E10) due to the lowering of BCS resistance (RBCS). Simultaneous to the decrease in RBCS, an unpredictable variability in cavity Q’s has been observed in both fine grain and large grain SRF Nb cavities that has been attributed to increases in residual resistance...
