The maximum accelerating gradient of SRF cavities can be increased by raising the field of full flux penetration, Hvp. One method which can potentially increase Hvp is to use structures consisting of alternating layers of superconductors and insulators (SIS). Magnetometry is commercially available but consists of limitations, such as SQUID measurements which apply a field over both superconducting layers, so Hvp cannot be measured. If Hvp is to be measured for SIS coatings, a parallel, local magnetic field must be applied from one plane of the sample, with no field on the opposing plane. A field penetration experiment has been developed at Daresbury laboratory allowing Hvp to be measured using a local, parallel DC magnetic field. Using a field much smaller than the sample allows limitations such as edge effects to be significantly reduced. By increasing the field, Hvp can be found by using 2 hall probes, one either side of the sample. The experiment was designed to use a variable temperature insert (VTI) to run in a cryogen free environment, but has been running in a LHe bath for thermal stability. © Published under licence by IOP Publishing Ltd.
Conference code: 161356
Export Date: 30 July 2020
Funding details: 730871
Funding text 1: The authors wish to acknowledge the support received from STFC and ASTeC management. O.B. Malyshev would like to acknowledge the support provided by European Unions ARIES collaboration H2020 Research and Innovation Programme under Grant Agreement no. 730871. The author also thanks to the team at Rutherford Appleton Laboratory consisting of Ben Green and Josef Boehm for wrapping the low temperature superconducting magnet coil, and joining the LTS wire to the HTS ribbon, and the HTS ribbon to the Cu rods.
References: Turner, D., (2019) Characterization of Flat Multilayer Thin Film Superconductors-19th International Conf. on Superconducting Radio Frequency.; Malyshev, O.B., A Facility for Magnetic Field Penetration Measurements on Multilayer S-I-S Structures (2015) 17th International Conf. on Superconducting Radio Frequency.; A. Gurevich. Enhancement of rf breakdown field of superconductors by multilayer coating. 2006 DOI: https://doi.org/10.1063/1.2162264; A. Gurevich. Maximum screening fields of superconducting multilayer structures. 2015. DOI: https://doi.org/10.1063/1.4905711UR - https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088136680&doi=10.1088%2f1742-6596%2f1559%2f1%2f012067&partnerID=40&md5=a288cf2ff22ecae23f154fe786b08223
