Abstract Body

In spite of the huge field and temperature advantages of HTS materials compared to Nb-Ti and Nb3Sn, only the most specialized laboratories yet house HTS user magnets. REBCO is the most easily applied conductor, yet 16 or 17 years after coated conductors became available in length, only one significant product line, the 1.1-1.2 GHz NMR magnets made by Bruker, is being installed, now in almost 10 labs. High conductor cost is one reason, but so too are important variabilities and deviations from the ideality of the conductor that greatly raise the complexity of its use. The anisotropy, both mechanical and superconducting, is difficult to measure and design of solenoid magnets hard to do properly without detailed knowledge of anisotropic properties of the tape. The recent development of practical torque magnetometers has greatly eased measurement and understanding of Ic(Q,B,T) but the fact that its magnitude and functional form isso strongly dependent on exact details of the nanostructure and hence the REBCO layer growth means that manufactured conductors made to the same specification often have widely different properties in the high field regime. There is an inherent tension between the desire to increase production rates, lower costs and tighten and reduce specifications. I want to explore some of these issues as they affect the characterizations that we are making of coated conductors used in test magnets made from coated conductors made from multiple sources. It is clear that reliance on Ic(77,SF) is no longer feasible but much less clear is what kind of specification, almost certainly of multiple properties, should or could replace this simple metric.

Acknowledgment

Support by US DOE-OHEP (DE-SC0010421, DE-SC0018666, DE-SC0018683, US DOE-OFES (DE-SC0022011), the NHMFL Core Grant (NSF 2128556 ), an FSU special allocation for Bi-2212 commercialization, the State of Florida, and the US DOE-MDP for much context and many collaborations.