Test results and perspectives of the cluster test program

The Cluster Test Facility has been constructed and successfully tested at the Japan Atomic Energy Research Institute (JAERI) for the development of superconducting tokamak toroidal coils. The Cluster Test Coils, constructed in 1980, are 20MJ, NbTi, pool-cooled coils. During the first test operation, the two coils were charged successfully to the rated current value of 2,145A without quenching. The detailed data obtained during the cool down was significant. This information pertains mainly to the efficiency of the cooling surface and thermal properties of the coil legs composed of stainless steel and glass epoxy. Results of strain measurements during the charging tests indicated a serious problem of analytical calculations. This problem arises primarily from the difficulty of defining the mechanical properties of winding-structure interface. The first test module coil is a 10T, Nb3Sn coil. This coil is now under construction and will be tested in the Cluster Test Facility in 1982.