Excitation of a Superconducting Coil Made of Ta-Reinforced Conductor in 14 T

We have been developing Ta reinforced Nb₃Sn superconductors. To demonstrate the conductor´s performance, we fabricated an epoxy-impregnated magnet and excited in the maximum background field of 14 T. The magnet showed training behavior. To estimate the relation between the premature quenches and epoxy resin´s cracks, we analyzed the mechanical stress during excitation of the magnet. Assuming the conductor in the innermost layer was not fixed to the bobbin due to the many cracks, the analytical stress data agreed well with the experimental results. Even if the conductor was not mechanically supported by the bobbin, it was showed that the quench currents of the magnet reached the critical current. We think that the Ta-reinforced conductor is useful in the case of large electromagnetic stress