Estimation of Current Decay Performance of HTS Superconducting Magnet Using YBCO Wire for Maglev

초록

Due to the potential cost down as well as better Jc-B-T characteristics and higher mechanical properties than BSCCO-based superconductor, YBCO-based superconductor(YBCO wire) is expected to bring higher magnetic performance, compact design and cost reduction of HTS superconducting magnet for Maglev. In developing the HTS superconducting magnet using YBCO wire for Maglev, one of the key performances to be considered is current decay performance at persistent-current mode operation, which is related to propulsion and levitation performance of Maglev. From this reason, preliminary evaluation for the current decay performance is necessary to determine feasible structure of the HTS superconducting magnet. This paper deals with estimation of current decay performance to be expected on pancake magnets designed with YBCO. The pancake magnets in this study were designed with the mechanical properties and Jc-B-T data which currently available YBCO wire in market has, and dimensioned to be able to have same electromagnetic forces for levitation and propulsion. However, each magnet had different numbers of superconducting joints due to their design structures. The estimation of the current decay performances was carried out by numerical calculation with total resistance and inductance expected on each magnet. To estimate the total resistance of each magnet, joint resistance for possible joint structures of YBCO wire was investigated at the cooling temperature of 77oK. From the study, a feasible magnet structure to achieve acceptable current decay performance for Maglev is presented.