The NHMFL Hybrid Magnet Projects

The National High Magnetic Field Laboratory is developing resistive-superconducting hybrid magnets both for internal use and for installation at other facilities. The Tallahassee magnet will have a vertical bore and provide 36 T in a 40-mm bore with 1-ppm homogeneity over a 10-mm diameter spherical volume. The Berlin version will provide a horizontal field of 25 T in a converging-diverging bore configuration suitable for neutron-scattering experiments. A design study is underway for a third magnet for Oak Ridge that will be similar to the Berlin version but provide $>$30 T. The three magnets will use very similar $\sim$13 T ${\rm Nb}_{3}{\rm Sn}$ CICC coils for the superconducting outserts. The resistive insert magnets will be different configurations operating at different power levels. In designing the magnet systems we have developed a new numerical model to predict the critical current of ${\rm Nb}_{3}{\rm Sn}$ CICC's, tested several conductors in-house and abroad, designed cryostats and refrigeration systems, and developed new resistive magnet technology. An overview of the innovations and present status is presented.