Hot Spot Behavior of Y123 Coated Conductors

We measured the time evolution of voltage and temperature of a CVD-Y123 coated conductor monolayer coil with Cu stabilizer under the cryocooled condition. The thermal runaway occurred locally at operate currents of 1.05-1.3 at 38 K and 1-10 T. In this case, the hot spot originated from the inhomogeneity of was observed. The thermal runaway generated from different parts of the tape at high and low fields at 38 K, respectively. This is due to the different heating behavior related to the distribution. The critical heating power of the thermal runaway obtained in this study were about 30 mW at 38 K and 10 T. It weakly depends on magnetic filed but is independent to the temperature. The analysis suggests that the cooling condition for the transient phenomena such as the thermal runaway is poor.