Challenges of high field large bore superconducting “outserts” for research magnets.

The development of high temperature superconductors (HTS), with high critical fields at 4.2 Kelvin (K), has opened up a new experimental space: the investigation of the properties of matter within static magnetic fields > 22 Tesla (T). This has driven the requirement for large bore, high field “outsert” solenoid magnets, using more conventional NbTi and Nb3Sn conductors to provide the background field, within which an HTS coil can operate. We will discuss the challenges which have to be met to provide such compact, high field superconducting magnets, including quench energy management, coil interactions, mechanical support, eddy current forces and cryogen handling, and how they have been successfully overcome with the development of 19T, 150mm bore (Hochfeld-Magnetlabor Dresden, HLD) and 15T, 250mm bore systems (All superconducting 32 Tesla program at the National High Field Magnet Laboratory, Florida, NHMFL). We will also discuss where this emerging technology can be further developed for the next generation of experiments.