Buffered Electropolishing -- a New Way for Achieving Extremely Smooth Surface Finish on Nb SRF Cavities To be Used in Particle Accelerators

TL;DR

Buffered Electropolishing (BEP) is a novel technique that produces extremely smooth niobium SRF cavity surfaces faster than traditional methods, promising improvements for particle accelerator applications.

Contribution

This paper introduces BEP as a new surface treatment for Nb SRF cavities, achieving unprecedented smoothness and higher removal rates than conventional electropolishing.

Findings

BEP produces the smoothest Nb surface finish reported.

BEP removal rate reaches up to 4.09 μm/min, faster than traditional methods.

Ongoing tests on RF cavities to validate surface quality improvements.

Abstract

A new surface treatment technique for niobium (Nb) Superconducting Radio Frequency (SRF) cavities called Buffered Electropolishing (BEP) has been developed at JLab. It was found that BEP could produce the smoothest surface finish on Nb samples ever reported in the literature. Experimental results revealed that the Nb removal rate of BEP could reach as high as 4.09 um/min. This is significantly faster1 than that of the conventional electropolishing technique employing an acid mixture of HF and H2SO4. An investigation is underway to determine the optimum values for all relevant BEP parameters so that the high quality of surface finish achieved on samples can be realized within the geometry of an elliptical RF cavity. Toward this end, single cell Nb cavities are being electropolished with BEP electrolyte at both CEA-Saclay and JLAB. These cavities will be RF tested and the results will be reported through this presentation.