Surface analyses and optimization of centrifugal barrel polishing of Nb cavities

Detailed microscopy investigations of the niobiumsurface quality after centrifugal barrel polishing (CBP)have been performed applying metallographic techniques.The results imply the need for further optimisation of thepolishing procedure, mainly to reduce the thickness of thelayer that is damaged at the surface as well as pollution bythe polishing media. The most realistic application ofCBP is a combination using CBP initially to removesurface defects followed by chemical polishing to obtain achemically clean niobium surface