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We have been developing conduction-cooled HTS magnets wound with REBCO-coated conductors for MRI systems, with the aim of developing 9.4 T MRI magnets for whole-body and brain imaging. One of a key technology to implement the REBCO coil is quench protection and we proposed a quench protection method using electrically conductive epoxy resin [1]. The electrically conductive epoxy resin is attached to the edge of the winding. When the coil voltage rises unintentionally, the excessive current can be automatically bypassed from turn to turn through the electrically conductive epoxy resin. In order to verify the effectiveness of this method with a large-scale coil which has higher stored energy, an HTS MRI model magnet equipped with conductive epoxy resin was designed and fabricated. The magnet has a REBCO multi coil composed of 100 single pancakes whose inner diameter are 500 mm. The total conductor length is 31 km, and the total inductance is 91 H. The central magnetic field is 3 T at 145 A, and the size of the homogeneous magnetic field region is 200 mm diameter spherical volume (DSV). This paper presents the design, fabrication of the REBCO multi coil and test results of the HTS MRI model magnet in a conduction-cooled configuration.
[1] H. Miyazaki, S. Iwai, et al: “Study on a Stacked REBCO Coil Composed of Six Single Pancakes with Electrically Conductive Epoxy Resin,” IEEE Trans Appl. Supercond., vol. 30, no. 4, Jun. 2020, Art. no. 4704105.
