Krishnan, M. Chapman, S.F. Irfan, I. Spradlin, J.K. Tian, H. Velas, K.M. JACoW Geneva, Switzerland 978-3-95450-178-6 10.18429/JACoW-SRF2015-TUPB034 English 633-637 TUPB034 cavity SRF ion plasma cathode Contribution to a conference proceedings 2015 2015-12 http://dx.doi.org/10.18429/JACoW-SRF2015-TUPB034 http://srf2015.vrws.de/papers/tupb034.pdf Alameda Applied Sciences Corporation (AASC) grows Nb thin films via Coaxial Energetic Deposition (CED) from a cathodic arc plasma. The plasma consists of 60-120eV Nb ions (Nb+ and Nb++) [1] that penetrate a few monolayers into the substrate [2] and enable sufficient surface mobility to ensure that the lowest energy state (crystalline structure with minimal defects) is accessible to the film [3]. One limitation of CED thinfilms is the presence of Nb macroparticles (~0.1-10 microns) that could be deleterious to high field performance of the SRF cavity. One way to remove such macroparticles [4] is to grow a thick film (~3-5 microns), followed by mechanical polishing (MP) using the finest media as might be applied in Centrifugal Barrel Polishing (CBP) to achieve a 0.4 micron surface figure, and an electropolishing (EP) step to remove ~1 micron of Nb that also removes all traces of embedded media in the film. The residual 2-4 micron Nb film should more nearly resemble the surface of a bulk Nb cavity that has been subjected to the same steps. This paper describes experiments conducted on Cu coupons as a prelude to an SRF Cu cavity coating.