Quench initiation and propagation characteristics of HTS wires under liquid nitrogen cooling condition

With the successful commercialization of Bi-2223 powder-in-tube tape and the improving quality & length-scale of YBCO coated tape, HTS magnets for high magnetic field and electric power applications have been developed. Although the operating temperature of HTS magnets must be kept in the designed level, the magnetic energy and mechanical disturbances can cause a thermal run-away. Especially, heat energy generated in the inner HTS winding is apt to accumulate, so a normal region appears in the HTS winding. This paper deals with the quench initiation and propagation characteristics of Bi-2223 wires and YBCO coated conductor, cooled by liquid nitrogen in adiabatic condition. A NiCr heater, mounted onto the surface of the HTS wire was used to provide the artificial heat that initiated quench. The quench characteristics of HTS wires were mainly affected by the material type and the superconductor to matrix ratio.