Division of accelerators, cryogenics and magnetism

Over the years, Nb/Cu technology, despite its shortcomings due to the commonly used magnetron sputtering, has positioned itself as an alternative route for the future of superconducting structures used in accelerators. Recently, significant progress has been made in the development of energetic vacuum deposition techniques, showing promise for the production of thin films tailored for superconducting radio-frequency (SRF) applications. JLab is pursuing energetic condensation deposition via techniques such as Electron Cyclotron Resonance and High Power Impulse Magnetron Sputtering (HiPIMS). Nb films with RRR comparable to bulk values are readily produced. The influence of the deposition energy on the material and RF properties of the films is investigated with the characterization of their surface, structure, superconducting properties and RF response. Nucleation studies are investigating the best conditions to create a favorable template for growing the final SRF surface.  This presentation will report results on surface impedance measurements correlated with surface and material characterization for Nb and multilayered SIS films produced on a variety of substrates. A progress report on work on NbTiN based multilayer structures will also be presented.