Nb3Sn Deposition for RF Analysis

The proposed Ph-II research project will be led by Alameda Applied Sciences Corporation, in collaboration with Jefferson National Accelerator Facility (JLab) and Norfolk State University (NSU) via subcontracts. This team covers the gamut of fundamental research into new Superconducting Radio Frequency (SRF) materials: (i) to first characterize the materials properties such as morphology, grain size, crystalline structure, defects, and impurities; (ii) to then measure electrical properties such as Tc and RRR; (iii) to follow this with `in-cavity¿ measurements of the Surface Impedance of the films at cryogenic temperatures. These three progressive steps are essential preludes to design of actual SRF cavities for eventual testing at high fields in accelerator structures, to measure Q-slope and other performance parameters. In Ph-I, AASC took the first steps towards development of Nb3Sn as a new type of SRF thin-film, to complement our earlier successful results with pure Nb films. One breakthrough of this Ph-I project is that we have produced Nb3Sn films in a single step in vacuum, by judicious choice of source composition for a given substrate temperature. In parallel with the Nb3Sn coating development, we continued to deposit pure Nb films using our CEDTM process and these films were analyzed by our partners JLab and NSU. This collaboration has had a paper accepted for publication in JVS, which describes large (~50µm) crystal grain sizes (unprecedented) in thin-film Nb deposited using our proprietary CEDTM cathodic arc technique