It is generally agreed that the development of a self-protective MgB2 magnet may not be achieved because of the slow normal-zone propagation velocity of the MgB2 wires, compared to their low-temperature superconductor counterparts. However, the use of the no-insulation (NI) winding technique can allow the MgB2 magnet to be self-protecting, because the excessive heat and current generated by local quenching can be automatically bypassed through the uninsulated turns. Nevertheless, to utilize the NI winding technique for large-scale superconducting magnets such as whole-body MRI magnets, it is essential to ameliorate the charging/discharging delays observed in the NI windings. As an alternative solution, this study examines a partially insulated (PI) MgB2 magnet that employs layer-to-layer insulations only, in the absence of turn-to-turn insulations. A monofilament MgB2 wire manufactured by Kiswire Advanced Technology Co. Ltd., was used for the fabrication of the PI MgB2 magnet. The charge-discharge and over-current characteristics of the PI MgB2 magnet were investigated to demonstrate the feasibility of employing the PI winding technique to develop a self-protective MgB2 MRI magnet with fast charging/discharging rates.
Acknowledgement: This work was supported by the Materials and Components Technology Development Program of KEIT [10053590, Development of MgB2 wire and coil with a high critical current and long length for superconducting medical•electric power equipment].
|Submitters Country||Republic of Korea|