Quench Behavior of YBa2 Cu3O7 Coated Conductor With AC Transport Current

Alternating current (ac) loss and quench behavior measurements were performed on a YBa₂Cu₃O_x coated conductor at 45 K. The minimum quench energies (MQEs) and the quench propagation velocities were measured as a function of transport current and frequency. AC losses were measured at the corresponding temperature and frequencies to quantify the internal thermal load during ac quench measurements. It was found that the direct current (dc) and ac quench behavior are similar, but that the MQE for dc experiments is higher than the corresponding ac cases. This difference is not seen in the normal zone propagation velocity data, indicating that the difference in MQE is minimal if the ac losses are included in the energy calculation. The ac experiments show that the MQE and propagation velocity varies weakly with frequency.