Effect of Sensor Length on Thermal Response of External-heating-type MgB2 Level Sensor for Liquid Hydrogen

Hydrogen is attracting attention as an alternative energy source to fossil fuels and nuclear power. Liquid hydrogen (LH2) with a density of about 800 times that of gaseous hydrogen is suitable for transportation and storage. The precise measurement of liquid level is important for liquid hydrogen management. The authors have developed an external-heating type superconducting MgB2 level sensor and previously reported the thermal response of an 800-mm-long MgB2 level sensor. However, the effect of sensor length on thermal response is not clear. To clarify the effect of sensor length, the authors examined the thermal response of a 200-mm-long MgB2 level sensor as parameters of heater input and liquid level. It was found that the thermal response of the MgB2 level sensor was independent of both parameters regardless of the sensor length. Moreover, the thermal response of the MgB2 level sensor was excellent at a heater input of 6 W and above.