Investigations on a prototype of high temperature superconductor cryogenic current comparator with a toroidal shield

Studies are in progress towards a liquid nitrogen current cryocomparator able to reach uncertainties comparable with the ones achieved by the liquid helium cryocomparators. For the shielding the ceramic high-temperature superconductor YBCO is employed. To overcome the difficulties arising in machining ceramic materials to reproduce the shield geometry adopted in liquid helium cryocomparators, investigations are carried out on a shield prototype adopting: a technique to obtain the shield as a YBCO layer anchored to a metallic substrate: a suitable toroidal shape allowed by this technique and studied via analytical and numerical approaches.