R&D Progress in SRF Surface Preparation With Centrifugal Barrel Polishing (CBP) for Both Nb and Cu

Centrifugal barrel polishing (CBP) is becoming acommon R&D tool for SRF cavity preparation aroundthe world. During the CBP process a cylindricallysymmetric SRF cavity is filled with relatively cheap andenvironmentally friendly abrasive and sealed. The cavityis then spun around a cylindrically symmetric axis athigh speeds uniformly conditioning the inner surface.This uniformity is especially relevant for SRF applicationbecause many times a single manufacturing defect limitsa cavity’s performance well below it’s theoretical limit.In addition CBP has created surfaces with roughness’s onthe order of 10’s of nm, which create a unique surfacefor wet chemistry or thin film deposition. CBP is nowbeing utilized at Jefferson Lab, Fermi Lab and CornellUniversity in the US, Deutsches Elektronen-Synchrotronin Germany, Laboratori Nazionali di Legnaro in Italy,and Raja Ramanna Centre for Advanced Technology inIndia. In this report we present the current CBP researchfrom each lab including equipment, baseline recipes, cavityremov al rates and subsequent cryogenic cavity tests onniobium as well as copper cavities where available