PROJECT SUMMARY Advanced brain research demands ultra-high field MRI systems. The 11.7 T Neurospin CEA MRI magnet pushed the use of superconducting NbTi materials to the limit by using superfluid helium to cool. To design and build a cost effective 16 T head-only MRI magnet, Nb3Sn wires must be used. To reduce the risks with such a high-field, high-stress, and high-stored energy magnet, critical technologies must be developed before a 16 T MRI system can be realized. One of the biggest risks is the cracking of the Nb3Sn coil composite matrix under high mechanical and thermal stress. GE Research will design and test Nb3Sn test coils under high background magnetic fields (~8.5 T) to evaluate the integrity of novel ceramic-fiber insulation composite matrix under high mechanical and thermal stress. Persistent joints on unreacted Nb3Sn wires, reacted wires, and NbTi to Nb3Sn wires will be developed and tested under external magnetic fields. Joint resistance is targeted to be <10-10 - 10-9 for the magnet to operate in a persistent mode.