We are currently developing an external-heating-type superconducting magnesium diboride (MgB2)-level sensor for a large liquid hydrogen tank as one of the basic technologies for the marine transportation of liquid hydrogen. Optimization of the sensor performance and effect of sensor length on thermal response were previously reported. However, the performance variation of the MgB2 sensor caused by individual differences in the wire rod has not yet been clarified. In this study, we developed a simultaneous calibration system for five MgB2-level sensors, and examined the level-detecting characteristics of five 500-mm-long MgB2-level sensors. It was found that the maximum performance variation of the MgB2 sensors was about 2% for the full scale of the sensor length, although the four fifth sensors indicated the same results. Therefore, the performance variation in MgB2 sensors caused by individual differences in the wire rods was minimal.
