POST-PROCESSING OF Nb3Sn COATED NIOBIUM*

Practical SRF cavities may be subjected to one or more processes after nominally complete preparation. Successful implementation of such processes in Nb3Sn coated cavities requires the understanding of material’s response to these treatments. SRF-grade Nb samples, coated with Nb3Sn by the widely used tin vapor diffusion process were subjected to one or more of the following: hydrofluoric acid (HF) rinsing, oxypolishing, buffered chemical polishing (BCP) or electrochemical treatment. They were examined by materials characterization techniques including scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The effects compared to niobium are different enough in most cases that further development is desirable to routinely obtain a favorable result.