An HTS Model Magnet for MRI Systems Equipped With Electrically Conductive Epoxy Resin for Quench Protection

Abstract

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 the key technologies to implement the REBCO coil is quench protection and we proposed a quench protection method using electrically conductive epoxy resin. 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 that has higher stored energy, an HTS MRI model magnet equipped with conductive epoxy resin was designed and fabricated. The magnet has a REBCO multicoil composed of 100 single pancakes whose inner diameters 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 142.7 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 multicoil, and test results of the HTS MRI model magnet in a conduction-cooled configuration.