Characteristics of the kA class superconducting coil with high winding tension

For the development of the 0.7 MJ small-sized superconducting magnetic energy storage (mu SMES) device, quench currents of a kA class superconducting cable were tested for various winding tensions because a dry superconducting coil is usually quenched by an abrupt heat pulse due to strand motions. The test coil similar to parameters of the optimally designed 0.7 MJ mu SMES except a stored energy and a size was fabricated based on the test results of the kA class superconducting cable and tested. These experimental results show that the highly prestressed test coil has an excellent DC performance in spite of a dry type coil but the quench current is much degraded even at the low field ramping rate of about 0.4 T/s.