Acid Free Extended Mechanical Polishing R&D

Extended Mechanical Polishing (XMP), as described in this paper, may be a pathway to eliminate chemistry from the elliptical SRF cavity processing sequence. It would be beneficial to remove chemistry after the XMP process because it would be more environmental friendly, would require much less infrastructure and would be less technically involved, opening up avenues for cavity processing at more industrial partners and facilities in general. Also the XMP process would be cheaper without the post-XMP chemistry step. Recent results on cavities processed by the fine polishing of XMP and followed by no chemistry show that the fine polishing does not have much if any negative effect on cavity performance. Recent attempts to remove contamination introduced in the bulk material removal and rough polishing steps of the XMP process shows need for further improvement. This paper describes the XMP process, optimization experiments, and resulting cavity tests that that showed Q0 close to 3x10 10 and EACC over 30 MV/m.