Extreme diffusion limited electropolishing of niobium radiofrequency cavities

Water diffusion coefficients during copper electropolishing

Cu electropolishing was studied using a rotating disc electrode in a variety of phosphoric acid-based electrolytes, including several with ethanol and other species added as diluents. Diluents allow a wider range of water concentrations and electrolyte viscosities to be accessed and also reduce the removal rate during Cu electropolishing, simplifying possible application to damascene processing...

Modeling, Fabrication, and Optimization of Niobium Cavities: Final Phase

Development of Seamless Niobium Cavities for Accelerator Applications*

Superconducting niobium cavities for application in particle accelerators are usually fabricated by standard techniques such as forming of subcomponents by deep drawing and joining by electron beam welding. Even though these techniques are being used successfully in many larger-scale accelerator projects and improvements in accelerating gradients have been achieved over the last several years, ...

Optimization of Chemical Etching Process in Niobium Cavities

Superconducting niobium cavities are important components of linear accelerators. Buffered chemical polishing (bcp) on the inner surface of the cavity is a standard procedure to improve its performance. The quality of bcp, however, has not been optimized well in terms of the uniformity of surface smoothness. A finite element computational fluid dynamics (cfd) model was developed to simulate the...

Anisotropic Thermal Conductivity of Polycrystalline Niobium for Superconducting Cavities

This study investigates the thermal conductivity Κ of polycrystalline niobium. We recall that superconducting cavities for particle accelerators are made of niobium. And, the thermal conductivity Κ is one of the factors which play an important role in the cooling of these cavities by the surrounding superfluid helium bath. Our experiments revealed a rather unexpected discrepancy in the thermal ...