Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
Cockcroft Institute, Warrington, Cheshire, United Kingdom
Lancaster University, Lancaster, United Kingdom
INFN/LNL, Legnaro (PD), Italy
TRIUMF, Vancouver, Canada
UVIC, Victoria, Canada
University Siegen, Siegen, Germany
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
Riga Technical University, Riga, Latvia
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
IEE, Bratislava, Slovak Republic
CERN, Meyrin, Switzerland
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
University Siegen, Siegen, Germany
MNaF, Siegen, Germany
HZB, Berlin, Germany
University of Siegen, Siegen, Germany
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
In recent years, the use of alternatives to bulk Nb in the fabrication of SRF cavities, including novel materials and/or fabrication techniques, have been extensively explored by the SRF community. One of these new methodologies is the use of a superconductor-insulator-superconductor (SIS) multilayer structure. Typically, these have been envisaged for use with bulk Nb cavities. However, it is conceivable to combine the benefits of SIS structures with the benefits of coated Cu cavities. It is also clear that the use of energetic deposition techniques such as high power impulse magnetron sputtering (HiPIMS), provide significant benefits over typical DC magnetron sputtering (MS) coatings, in terms of SRF performance. In light of this, two series of multilayer SIS film coatings, with a Nb-AlN-NbN structure, were deposited onto electropolished OFHC Cu samples, with the use of HiPIMS, in order to determine the efficacy of this approach. This contribution details the development of these coatings and the required optimization of the coating parameters of the separate material systems, through the use of multiple material and superconducting characterization techniques.
University Siegen, Siegen, Germany
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
As part of efforts to improve the performance of SRF cavities, the use of alternative structures, such as superconductor-insulator-superconductor (SIS) film coatings have been extensively investigated. Initial efforts using DC magnetron sputtering (MS) deposited NbN films showed the efficacy of this approach. The use of energetic condensation methods, such as high power impulse magnetron sputtering (HiPIMS), have already improved the performance of Nb thin films for SRF cavities and have already been used for nitride film coatings in the tool industry. In this contribution, the results from the deposition of HiPIMS NbN thin films onto oxygen free high conductivity (OFHC) Cu substrates are presented. The effects of the different deposition parameters on the deposited films were elucidated through various characterisation methods, resulting in an optimum coating procedure. This allowed for further comparison between the HiPIMS NbN films and the previously presented DC MS NbN films. The results indicate the improvements offered by HiPIMS deposition, most notably, the significant increase in the entry field, and its applicability to the deposition of SIS films on Cu.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
CEA-IRFU, Gif-sur-Yvette, France
INFN/LNL, Legnaro (PD), Italy
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
Lancaster University, Lancaster, United Kingdom
HZB, Berlin, Germany
University Siegen, Siegen, Germany
Riga Technical University, Riga, Latvia
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
Cockcroft Institute, Warrington, Cheshire, United Kingdom
CERN, Meyrin, Switzerland
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
An international collaboration of research teams from CEA (France), CERN (Switzerland), INFN/LNL (Italy), HZB and USI (Germany), IEE (Slovakia), RTU (Latvia) and STFC/DL (UK), are working together on better understanding of how to improve the properties of superconducting thin films (ScTF) for RF cavities. The collaboration has been formed as WP15 in the H2020 ARIES project funded by EC. The systematic study of ScTF covers: Cu substrate polishing with different techniques (EP, SUBU, EP+SUBU, tumbling, laser), Nb, NbN, Nb3Sn and SIS film deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application of all obtained knowledge on polishing, deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application to the QPR samples for testing the films at RF conditions. The preparation, deposition and characterisation of each sample involves 3-5 partners enhancing the capability of each other and resulting in a more complete analysis of each film. The talk will give an overview of the collaborative research and will be an introduction to the detailed talks given by the team members.