A Computational Study to Find an Optimal RRR Value for a 1.5-T Persistent-Mode Conduction-Cooled MgB 2 MRI Magnet From a Quench Protection Point of View

The effect of magnetoresistance, magnetothermal conductivity (MTC), and RRR value on the active quench protection of a persistent-mode conduction-cooled 1.5 T MgB
₂
superconducting magnet is studied using numerical simulation. It is found that inclusion of magnetoresistance in the simulation can significantly decrease the calculated maximum temperature reached in this magnet during a quench, e.g., by 9 K for RRR = 100. The inclusion of both magnetoresistance and MTC similarly decreases the peak temperature, but by a smaller amount, e.g., by 7 K for RRR = 100. Using copper with a lower RRR value can also significantly decrease the peak temperature reached in this magnet, e.g., by 16 K for RRR = 50 as compared to RRR = 200. However, decreasing the RRR value to much less than 50 results in a significantly higher voltage, e.g., decreasing the RRR value from 50 to 10 results in a 1000 V increase. A RRR value between 50 and 100 may provide a good balance.