Development of a liquid hydrogen transfer pump system with MgB_2 wires

摘要

An electric pump composed of an MgB_2 motor is combined with superconducting level sensors using thin CuNi-sheathed MgB_2 wires to transfer liquid hydrogen. An impeller is attached to the lower end of a rotating shaft on the MgB_2 motor and covered with an outer casing to form a centrifugal pump. Then, the MgB_2 motor and impeller are placed vertically inside a cryostat with an infill of liquid hydrogen. A glass Dewar vessel is prepared to receive the liquid hydrogen transferred from the cryostat containing the MgB_2 motor. The MgB_2 sensors are used not only to detect the level of liquid hydrogen but also to control the electric pump on the basis of their pre-estimated calibration curves. By using the assembled pump system, the liquid hydrogen is successfully transferred from the cryostat to the glass Dewar vessel via a transfer tube.