LIQUID HELIUM LIQUID LEVEL METER

PURPOSE:To elevate the liquid level detection sensitivity of liquid helium, by detecting a signal component corresponding to the inductance of a coil wound around a superconductive element inserted vertical to the liquid level of the liquid helium. CONSTITUTION:A coil 11 is wound closely on the circumference of a superconductive element 4 from the upper to lower end thereof. Then, to mea sure the inductance of the coil 11, a inductance measuring device 15 is provided having a bridge circuit 12, an oscillator 13 as driving power source for the circuit 12 and a select amplification detector 14 for detecting a signal component corresponding to the inductance of the coil 11 generated when the circuit 12 is unbalance. Then, an arithmetic unit 16 calculates the liquid level of a liquid helium 2 from the inductance value output of the measuring device 15. In other words, the element 4 becomes superconductive in the liquid helium 2 (complete diamagnetism) while the part above the liquid surface 3 normally conductive. Thus, the inductance value of the coil 11 is detected utilizing the fact that the element 4 turns to complete diamagnetism according to the level of the liquid surface 3 thereby elevating the liquid level detection sensitivity.