Experimental Study on Superconducting Level Sensors for Cryogen Composed of MgB2 Wires with Stainless Steel Sheath Material

The operation of level sensors for cryogenic liq- uid with magnesium-diboride (MgB2) superconducting wires is experimentally simulated. The wires have the cross-sectional structure of a mono-cored MgB2 superconductor surrounded by a stainless steel material. The experiments are carried out in the liquid helium with boiling temperature of about 4 K at atmospheric pressure to validate the performance of the fabricated level sensors. Since the MgB2 superconductor has the critical temperature of about 39 K, this type of sensor is also expected to detect the level of liquid hydrogen with boiling temperature of about 20 K at atmospheric pressure.