Experiment of 10-T, 60-cm-bore Nb3Sn test module coil (TMC-1) for the cluster test program

A 60-cm-bore coil wound with a reacted multifilamentary Nb3Sn conductor, named as TMC-1, was constructed. A magnetic field of 10.2 T was successfully generated at a current of 6,056 A with a back-up field of 3.3 T from the cluster test coil. The total stored energy was 39 MJ. The strain of the Nb3Sn conductor was 0.67 % including a bending strain of 0.54 % during winding. Moreover, a 30-cm-length normal zone, nucleated by heater-input technique in the innermost turn, was recovered to superconducting state at 10 T. This means that a heat flux of conductor cooling surface is more than 1.08 W/cm². For the manual dump with a decay time of 14 second(B=0.48 T/sec.), the TMC-1 was stable without any damage. The TMC-1, which is pool-cooled at 4.2 K, is constructed as a step of the development of high field toroidal coil in a tokamak fusion machine. From thease results, it is demonstrated that multifilamentary Nb3Sn conductor is applicable to large-current and large-size coil.